2) Use an ergonomic split keyboard of some sort so your posture is much more relaxed and you're not hunched up trying to type on a straight keyboard.
Those two things will get you a long way. You can worry about other productivity improvements after that, but honestly I think they will be incremental once you've done the above.
Other fast gimme. Remap the capslock key to something useful but usually more awkward to reach. I've remapped it to ctrl, but considering switching to esc as I'm a vim user. Mind you, I've also got a FS3-P USB Triple Foot Switch Pedal under the desk with one of them mapped to esc, so not so urgent there. I wouldn't go remapping too much else otherwise it'll trip you up too much whenever you're at someone else's keyboard.
I learnt to touch-type in 1986 on a mechanical typewriter in school. I knew I was going to work with computers and so knew touch typing would be a valuable skill. I was the only male in the class as everyone else perceived it as a class for women looking to go into secretarial work.
I am absolutely amazed that touch typing is no longer taught in school in this age of ubiquitous computing.
As far as split keyboards, I love my MS Natural Ergonomics 4000. If I could get one with the number pad cut off (less reach for the mouse) it would be perfect. They do tend to last and last which is good as they're getting harder to find when one finally breaks. I've tried the MS Sculpt but I find the mushy esc key a real drawback (again, vim user). Overall just not especially nice to type on. I also do use the function keys and the extra media keys on the 4000 a fair bit, so missed them on the sculpt.
One of the advantages of vim is you can do almost all the editing without having to move your hands from the keyboard. You don't event have to move to the arrow keys as you can use hjkl for movement. Once learnt, it can be very efficient.
If I hand the time and energy, I would consider learning the Colemak layout. Given vi is hardwired into my brain by now I suspect it would make Dvorak too awkward.
Funny story. Once you can touch-type, you learn to unconsciously position your hands properly by feeling for the little marks on the J and F keys. When I worked in Japan, they didn't have these marks and I was forever drifting my hands over they keyboard until getting annoyed and having to look down to put my hands on the right row. You don't realise how many times a day you rely on that.
It wasn't until one of the locals pointed out to me that the curve of the J and F keys was deeper than the other keys on their keyboard that that particular stressor was solved. I learned to feel for that instead.