1) With the recent Palm VM available you basically can have a built in replacement for your dead Palm device.

2) I use the GPE suite and sync my calendar with Ermining. Works for me (though I can't do contacts but the recent Palm thing deals with that problem.

3) Battery life. if you are very carefull with how you use your tablet it will run all day (8+ hours) on a single charge. To do this you need to reduce the amount of time that the N800 is doing any of the following:

a) searching for a network connection. If you know you'll be out of range of WIFI or are in transit and don't need it. put the machine in offline mode and then lock the keyboard and screen. I have found that my N800 was trying to get online cause some app tried to initiate a network connection and then that "searching" process ate the battery. Also any time your wireless and bluetooth are off you are saving battery.

b) avoid websites that have flash animations like the plague. They will often spike the CPU usage which in turns kills battery. Many sites terms of service explicitly state you "cannot" block advertising. My philosophy is you either provide me with a decent non-flash page, buy me a new battery or it sucks that you have so much flash on your site cause I will block cpu hogging ads at will.

c) keep the screen brightness down to a minimum.

d) Keep your reboots to a minimum. Each time this thing boots a process kicks off that spikes the CPU for an extended amount of time. The more media files you have on your system the longer it takes to scan.

e) purchase a Solio. I am a happy customer. It will trickle charge your device on sunny days and provide you with emergency power should your tablet go wonky. I once used my Solio on a trip from Georgia to NJ and ran the iPod off the sun the entire trip (the battery was near dead at the beginning of the trip. Similarly when I headed to Florida I used the Solio to keep the N800 running when I had to reboot due to a MaemoMapper "issue" which cost me much battery power.