try out the mgetty pacakges, they can be hacked together to do what you need (make sure to get the fax enabled one) other than that you could write a quick daomon that looks for the phone ring signal and then plays a sound and reads /dev/input/event* and picks up on a button push. it depends on how they divide up the buttons (if its all one device then you may need a work around
the fat thing is a known problem, that is why there is that spining ball thing, dont pull out before that disappears, if it still happens then it might be a faulty SD card, there are known problems with certin SD cards and PDAs, its well documented at aximsite.com
for the rotation thing that has to do with the CPU hitting 100% not "bad memory handeling" if you feel its a problem you can fiddle with the glyph cache settings and bump it up a bit, this helps in games as well
i would definiattly invest in the resco range of products (file browser and rego editor) as they can help with some things (like the umount and it has an fdisk )
widows CE (was a typo but i thoght i would leave it) is rock solid until you add 3rd party apps the more you add the more unstable it gets
also if you want to share stuff on a wlan then you need an http server (free ware) or an ftp server (dont ask me haw i got it, just know i got it ) you will also want to try and get a 3rd party connection app as the windows wifi one sucks, the one that came with my dell x30 is great and with a trip to xda developers and thier rom extraction tool you can rip it out of the ROMs on dell, the other option is the socket connect app but it hides details and tries to look pretty. might also want the broadcomm bluetooth upgrade for wm5.0, it does wonders (bluetooth arvp a2dp and hid mouse/keyboard)