1. 2.1 is coming around Sept but that could change any time. 2.2 is only in the wishlist.
2 You can turn on the flash in the menu of the camera which is better than "flash in time" because the camera can adjust the exposure with flash on before actual taking the photo. Yes, it's inconvenience to go to menu to turn on the flash.
3. App killer is not needed to save battery in most cases, they actually reduce battery in long run. The exception case is when some app has a bug that keeps the OS awake, then and ONLY then app killer will help. Most sleeping apps don't use cpu at all, they might use some memory, but the memory doesn't use more battery when the values in the memory doesn't change.
4. Save battery is important, so I did many testing and finally got a good sense to have the best battery for x10. I have reset the x10 over 50 times to test this.
For the best battery, TURN OFF location, gps, bt, data, wifi, no widget, set the brightness to minimum, no sync at all, no background data, turn off market update (market->download->menu->do not notify), make sure no apps auto sync, don't use any app killer, no battery saving apps. With this, x10 should only use 0.5% / hour on idle, which equals 200 hours for a charge. Yes, it's pretty insane, try it. If it doesn't work, reset to factory, don't install any app, and try it again. You will be very happy, but it's time consuming to do these test.
FYI, WIFI uses more battery than 3G data, so if you want to use data, it's better to use 3G if your data plan is enough for your need. Location thru network has a bug which uses about 2 to 3% /hour on idle. I can go on and explain everything, but that will take 1 hr.
5. X10's only advantage is it's cheap to buy, and the 4" screen compare to other android and iphone.
6. what will be fixed in 2.1 all depends on how sony modify it. I sure rather sony doesn't do anything and give us stock 2.1. Search for the change log of 2.1 android.
7. Not sure, but why need wap?
8. JuiceDefender can help in battery, but it's complicated to use to actually save battery. I did really long test with different combinations of system settings with JuiceDefender to finally understand how Android works with 3G and Wifi.
Dolphin for browsing
ADW launcher is a must for x10. Tested over 10 different launchers already. Zeam is the second best for x10.
Switch Pro is pretty good, can control LED too.