I'm sure others will tell you differently, but my Treo 650 has been nothing but trouble since I got it and I'm on my second one.
The 300 was great, so was the 600, but both 650's have been lemons.
As for an answer to your question, check http://www.treocentral.com . If you search their discussion boards, you'll find an answer to any treo question imaginable. :)
Who needs it? I'm waiting for the combination cell phone, gps device, and PDA with internet access and voice recognition software at least as good as Dragon Naturally Speaking, and the present generation of PDAs should have more than enough compute power to run that sort of software. There's no excuse for trying to sell something with a keyboard which it would take a mouse or a gerbil to operate.
I don't think the 650 edits word docs etc. Its a PalmOS thing so it would have the same features as most any other PalmOS device.
The Treo700w is a PocketPC based device instead of PalmOS even though its made by Palm. Otherwise is very similar to the 650. Camera has more megapixels on the 700w but takes poorer pictures. 700w screen is slightly smaller resolution but I think thats why the battery life is higher.
I have the 700w and love it. I can surf the freerepublic in department meetings when things get a little long winded and pointless ;-)
Boss has the 650 he's a PalmOS guy.
I will say the PalmOS is more stable than Windows from what I've seen.
Hope some of that helped.
Happy Freeping.
It comes with an app called Documents to Go that will let you sync specified Office docs to the Treo and make modifications to them on the Treo.
It's kinda hard to do on such a small screen, but it's something.