Firstly batery life.I havent just sat down and played through ridge racers only so i cant confirm yet however i have played for 3 hours plus i watched about an hour of anime off of the memory stick.Thats at full brightness and speakers at 3/4 volume.I had it running in the main menu for quite a while as well putting stuff onto the memory stick.I can only asume that the 1hour 45 is while playing multiplayer with wireless lan.but even that is a little low. psp.ign.com have some really good battery life tests that show worst case scenerios.I think the average user is going to get at least 3h 20 min to 4 hours out of ridge racers.
Loading times are quite long though i have never timed them myself.While playing for me they are absolutly no problem i dont see how its that much of a problem.But ive never owned a portable before so im not used to carts.Also when powering down there are 2 modes.A tap of the power switch goes to standby and holding it down shuts down the system completly.You can go to standby at any time and then power up to where you left.The time it takes to start up is only a few seconds.This is a very cool feature and if i run out of time to do something where i cant save it like halfway through a race then you know you can always just goto standby.The standby mode only uses a very tiny amount of power so there is no need to worry about it running out.
The button are you talking about square or shoulder because ive had no problems with the square at all.The only problem is the squeekyness of the 2 buttons closest the screen(square being one) but that goes away after a little use.Most people are saying after a week it stopped.
The shoulder buttons have to be pressed down further than i would have liked.You cant just give them a slight tap.There is a deadzone for a bit before it works.I asume its so you dont bump them but compared to the xy buttons you have to press further.
There is a charger pack coming out which is a little hardcover case that can recharge the psp 3 times
http://psp.ign.com/articles/578/578449p1.html
There are also the rumours of bigger batteries being released.With the nyko case it isnt a problem for me because im never going to play in one sitting for longer than 3 1/2 hour away from a plug.
Hopefully a few things will be ironed out by launch.I highly recomend psp and cant express how much i really reallyenjoy this thing.