Thank you for the feedback! I will focus on learning Colemak for now then.

There are many questions there!

I only learnt how to touch type just over a year ago - and chose Dvorak.  In short because the layout appeared more ergonomic and widely supported across systems.  I personally hoped Dvorak and touch typing would alleviate personal pain - computer related injury.  I looked at Colemak - but in the end stuck with Dvorak.

You've picked up Dvorak very quickly - and reached a very good speed in no time at all.  It took me a long old slog to get my fingers dancing.  I'm still only keying around 60WPM - with the odd peak.  So hats off to you!  I still experience discomfort in my right shoulder, but can't say whether this is related to the layout or not. 

I can try and address a couple of points:

Shortcuts:
Just remember that CTRL+C, CTRL+X shortcuts are placed so you can key them with one hand and use the mouse with the other.  Which might not suit a lefty!

Using one hand for shortcuts can result in odd hand contortions that might not be so good in the long run - it's my understanding that you should use two hands ideally when using modifiers.

I also believe you are better shifting the mouse to the left hand to get better balance in front of a keyboard.  Only an issue for a keyboard that has a num-pad.  You can use CTRL + INSERT etc as an alternative to the left handed shortcuts.

As soon as you transparently reach out for keys - CTRL + C is just as easy in Dvorak, you just think the shortcuts and they happen.  I kept on closing the windows at first with Dvorak mixing up my V and W as @Dreymar says.  Not a problem now.  Q and W are adjacent to the command key on mac keyboards which is a bonus.

I do miss the ability to lazily use the keyboard with one hand - but it's the kind of thing that used to encourage me to adopt bad posture.  It can be a bit annoying if you don't change the key caps to visually identify shortcuts as well.  Though I don't fancy swapping the caps - as I occasionally use Qwerty.  Despite memorising the old layout  I am slow as anything touch typing it.

One issue when changing your layout is remapping shortcut keys in applications that have intentionally placed shortcuts on one hand (designed for Qwerty).  Games for instance, I normally choose to flip back to Qwerty - as I can't be bothered to reprogram keys.

Under Gnome on Linux - it's a simple matter of placing the backspace on the caps-lock key in whatever variant - it's not unique but rather inspired from Colemak - it might lesson the work on the right pinky.

Speed:
I perceived myself to be pretty fast as an ad hoc typist before transitioning to touch typing.  Though I never measured my rate.  I doubt I was near your speed.  I didn't think it was possible to really break 40WPM for sustained periods without touch typing.  I can only conclude that you must have agile fingers.

I'm not a speed demon and it's not my number one concern.  Comfort is.  Though I'm still not totally comfortable touch typing (curiously I never had finger, hand, or wrist problems when I used the hunt and peck method.)  I think some of my discomfort is just teething pain.  Things are getting better for me.

As a programmer I don't think my old typing method was a big show stopper.  I got by with many shortcuts, and in some ways was more innovative as a result.  You are forced to take shortcuts.  However I did get annoyed with the time it took to write emails etc.  From a productivity point of view, touch typing helps but I don't think it's the be all and end all.  There are also alternatives such as dictation software, using a Dictaphone and/or a personal assistant!  I haven't totally investigated it, but I'm sure predictive text and programmed shortcuts could really benefit non touch typists.

It sounds though that you are a quick learner and with the rapid progress you have made - it's worth sticking with.

Touch typing:
There are some plus points to blind typing, I think once you get to the point where you don't think about typing - it's one less barrier to what you are trying to achieve.  I like typing in the dark and not having to hunch over the keyboard.

Alternative layouts:
I've concluded that OSs don't cater that well for alternative layouts at this moment.  It should be trivial for the end user to switch and personalise their input methods.  It's painful and tedious.

Colemak vs Dvorak
I did try Colemak, but learnt the wide angle Colemak layout by accident - though I don't think that's necessarily a bad thing.  I did like it, but I felt I fumbled more than Dvorak.  I had got it into my head that Colemak must be better as it's newer than Dvorak.  However after investigating I haven't discovered a good scientific case for Colemak - just anecdotal evidence.  That's not to say that it might not be for you.  I'd suggest trying out a few and sticking with the one you prefer.  That's easier said than done though.  It takes me so long to get up to speed with a layout - it's difficult to try these things out.

Variants:
Many layouts have subtle variations.  UK and US Qwerty for instance.  Dvorak is different implementations on different operating systems.  This can be slightly annoying.

Mobiles:
If you are using one finger (or pointer) on a compact touch screen keyboard - I doubt you'll see much advantage running Dvorak compared with Qwerty - as you'd have to move the pointer further.  Plus you probably are visually tuned into Qwerty.  If you were to use two hands though - like a thumb keyboard - I could see an advantage in using Dvorak.  Perhaps you'd be better off learning a one handed layout - or something completely different more suited to a mobile.

Portability:
If you don't have to jump between systems then I think you can personalise your own PC to your hearts content.  There is someone on the forum that uses a Maltron and many of his own shortcuts to type incredibly fast with barely any effort.

I wish someone would standardise a portable format - so you can take your layout and shortcuts with you and apply them wherever you go.

That's nice. It took me two months to reach that speed.

In addition to specific letters or just at any time? What could a piece of text look like with that if you don't correct the errors?

If I understand it correctly, maybe try floating your hands. And if you have access to a keyboard with mechanical switches, maybe it's easier to feel/hear when you have depressed the key enough.

I agree very much with ctrl+backspace.

I haven't used Windows while I used Colemak, but back when I did, I did all sorts of remappings using AutoHotkey. It's not deeply embedded into Windows like it is if you do registry remapping, but it's very much easier (documentation and examples is on their web page) plus a lot more customisable. If you want to have your change apply across more things (maybe games), then the registry way is better, but I don't remember how to do that anymore.

That is weird! Maybe floating will also help :-)

I don't know if there is a right way to do it, but I simply meant don't rest the bases of your hands on the table/laptop/hand rest/whatever.

No probs :-)  I don't know if it's compatible,  but I don't see a reason it shouldn't be. Unless you need advanced scripting, I think any version will be fine as well. Registry remapping works on a level transparent to applications so they should work fine together (the registry can only move "whole" keys, so if you move the "1" key, "!" follows, but ahk can do much more including more fine grained control).

To increase accuracy you can try Typing of the Dead game, it has several accuracy drills which are really fun.

Or use Amphetype and set minimum accuracy to 97% or higher.

After sometimes, accuracy brings higher speed, since you will have to use backspace less and less.