I use a razr naga for my MMO gaming (it has 12 side number buttons, I assume yours has something similar? On warden I only bind 1 through 6 mainly for ease of use anyway).
I currently set it up so that the mouse wheel click is F8, the back button is F9 and the forward button is F10 (traditionally they would be the browsing buttons etc). I keep the number buttons bound to their numbers.
I then have the three basic builders on 1 - 3 (1 Sp, 2 Sh, 3 Fi). The 6 masteries I bind to the shift line (shift+1 - shift+6), the three double builders (SpSp etc) are on the ctrl line (ctrl+1 - ctrl+3) and my stances are bound to alt+1 - alt+3.
I then bind my gambit execution to F8, my gambit clear to shift+F8 and my four basic javelin skills (wages of fear etc) to F9, F10, shift+F9 and shift+F10.
Other skills such as ambush, battle prep, battle memory etc are dotted around anywhere from the basic 4-6 line on my mouse to ctrl+4-5 too.
I like this set up because it makes sense from a logical point of view, it is all really easy to access and it still leaves some room for customisation (which I reckon will be important come the class revamp in helms deep).
As for the class changes they have been pretty dramatic. I would just level up to cap to get used to the current state of things without getting overly worried because there's a good chance a reasonable amount will be changing come the next xpac. I suppose learning the benefits of assailment and the way our self buff gambits interact with each other especially when tanking would be the main areas of difference for you.
[color=#DBA901]Lieutenant Belegardo the Veteran, Reaver-Foe, Stalker-Foe, Blackarrow-Foe Rank 10 Warden
Skuttles, Black Dog, Rank 8 Weaver[/color]