Cell phones: (Another) Smartphone suggestions

(Another) Smartphone suggestions

I'm in the market for my first Smartphone-type device. I'm confused by the choices. Suggestions would be greatly appreciated.

How I would use it:

I'm not a big phone user. I don't want a contract! I would make the occasional call and rare text when traveling overseas (Europe). The main use would be to sync with my Google calendar and contacts via wi-fi. I would occasionally use it to check my email (an existing IMAP account). I would sometimes use it to listen to music and watch videos. I would prefer not to carry a separate PDA and phone.

Here are the details of what I'm looking for:

Required:
1) Can be bought without a contract (phone or data). I use about 5 phone minutes a week. I would like to be able to use my current T-Mobile prepaid Sim card.
2) It should be wi-fi compatible. I'm around a wi-fi signal all day.
3) Phone (US or Europe).
4) What I would really like it to do is sync with my Google calendar and contacts using wi-fi.
5) When traveling I would use it to check my email (existing IMAP and maybe POP) using wi-fi.
6) Play music and videos.

Would be nice:
1) Decent camera. 3+Mp.
2) Expandable memory.
3) GPS and maps. I'm confused whether I'd be able to use this feature without a data connection. It would be great if I could.
4) Compatible with Linux. I'm switching my computer over to Linux (Ubuntu), although I could always dual boot with Windows or use Wine just for the phone...
5) I would like it to be as portable (small) as possible, but with a usable keyboard and screen.
6) High quality (easy of use, durability, battery life, etc).

Ideally:
I could, in the future, sign up for a contract and use all the 3G bells and whistles. I'm willing to forgo this for now if it is not feasible.

Price range:
As low as possible, but I'm willing to pay a bit for the "perfect" phone.

Thank you very much in advance.