Using internet through bluetooth cellphone or aircard?

I recently switched job and this job requires me to have internet access on my laptop almost everywhere i go.

My question is..

(1) whether i should buy an extra PCMCIA aircard card like sonyericson's GC83 or i should simply use my cellphone which has bluetooth built-in to access internet? Any suggestion as of which method is better and why? Such as connection and signal wise?

(2) in term of battery consumption, will aircard or bluetooth use more power?

(3) i know if i use aircard, most likely i'll need 1 more sim card because i don't need to swap my sim card back and forth everytime i use it. But if i use bluetooth, will i be able to answer any incoming calls while i'm surfing?

(4) do i need to pay extra like data service plan if i use the bluetooth method even when i already have a cellphone monthly plan?

 

this is the only question I am able to answer:
on my configuration Acer Aspire 5024WLMi or iPaq h2210 - connected via Bluetooth to - Sony Ericsson K700i - connected via GPRS to internet ... I am able to answer/make calls or send/recieve sms... however while being on the call no data transfers are possible - all connections remain, but you do not get any data from/to internet...

 

An air card is the way to go if getting online often and reliably is the biggest concern. Veizon just dropped their plans to $60, I'd go that route, no question. I use one of their EVDO cards now and it's simply fantastic.

 

Do i expect to receive the same strength and speed in connection if i use either bluetooth method or aircard?

 

the bluetooth method is unreliable and bandwidth-limited (by your phone speed). the aircard is a much better solution. it's actually not even a comparison.