Advice for developing on a WP7 device without a phone plan

I'd like to start developing Win Phone 7 apps before it's too late. I'm not sure my motivation is high enough to do so without a physical device to play with, but I don't want to switch to T-Mobile or AT&T (US) to get a device.

I'm quite happy paying full retail price - but get left with a lot of questions.

• Will the device开发者_如何学运维 be fully functional without an active phone plan?
• Is it important to test on a device that has a physical keyboard
• Where is the best place to buy a retail price phone
• Will I still get system updates through wi-fi without an active phone plan - or can I just borrow a friend's AT&T SIM card when I know an update is available
• Are unlocked phones available - or are they still tied to the carrier

etc.

Preferably I'd like to be able to use the phone when in UK (less frequently than once a year)

• Yes - subject to not having network connectivity. You can still wifi for data.
• Not critical, you can emulate this with PAUSE in the emulator.
• Depends on your area.
• Updates through Zune when hooked up to your PC.
• I'm not aware of any carrier lock ins like iPhone.