You may try out 10MB and upgrade later if you find it not sufficient. The usage varies from user to user. 10MB does not enough to last for 2 days for my email usage.

u can browse pix on bb facebook without any problem.

it depend how much data u are fetching from facebook album. no problem with chinese character and u can install those character support from BB desktop manager.

Too bad Garmin only support North America and Europe only. No luck on other country.

If U found a 2nd hand BB. U can ask the seller to give u the device pin and IMEI. Then register it on your BIS provider. If can register, mean Pin is not locked.
U should tell seller that if pin not release, U not going to buy it.

Storm 9500 is low price "maybe" because:
1) touchscreen, no keypad: It make a huge different on typing speed. I can type much faster on my BB8900 than E71 or E61i.
2) No wifi like U said.
3) suretype- some users complaint it was hard to type compare to Iphone.

for step2 onward, U can just do it online. But make sure U already choose the BIS provider. Choose only 1
For maxis: http://maxis.blackberry.com/
For Celcom: http://www.mobileemail.vodafone.com.my/

REMEMBER: Choose only 1 BIS provider that U going to sub. Because once registered, to release U need to call the telco company the pin locked to.

To register BIS, U need to go respective service center to do the registration.

Actually you can decide on what sort of emails gets its contents pushed or only the headers. With the headers only option, you can also decide if you want to download the email content after the headers get pushed to you.

You can also decide what sort of emails get pushed to your device.

All these done using filters.