Keyboard: I use Swype - it takes a few minutes to get the hang of it, but the speed you gain with increased use is amazing. Watch some videos on youTube, it really is that fast. (It gives me an unfair edge when playing Pictionary with other people. ;] )
That said, the Swype version on my SGSII is outdated and I haven't found a way to update it.
You can teach it new words by typing them in letter by letter, and it'll include them in its algorithm. I'm still teaching it all the bad words, and Lebanese.
I don't know enough about the other things you asked, so I'll share some general stuff, which you probably already know:
Take a screenshot by pressing Home+Power
The notification bar at the top doubles as a screen brightness slider. Hold, and drag left-right to adjust brightness (the bar won't change into a slider, but you'll see the effect.) This is assuming you don't have it on auto-brightness.
Speaking of which, you definitely should not leave it on auto-brightness, as it's a battery eater. Besides, the screen is so monstrously bright that the lowest setting is enough when indoors.
Drag on the line of dots in the home screen to slide through your home screens and get a quick look at them - this is very useful when you've just got your phone, and have not yet memorised your screen layouts.
Click on one of the home screen dots to jump to it.
SGSII doesn't have a dedicated Search button, but you can hold down the Menu button to access Search.
Some nifty tips here
http://thehandheldblog.com/2011/06/14/galaxy-s2-tips-tricks/
