But the CDA region for P1i same as G900? 

Reflash your phone. Other phone's C:\ drives files might even crash your phone further. The whole UIQ3 OS is very delicate 
P1i has 3G (UTMS 2100) at 384kbps. It should be possible. There is a software called m-Router that is installed together when you install SE PC Suite, used to make P1i a modem for your PC.
All other questions can be answered on the first page. As for Wifi technology I will give a summary.

Wifi B (802.11b)
Release Date  - October 1999 
Op. Frequency - 2.4 GHz
Data Rate (Typ) - 4.5 Mbit/s
Data Rate (Max) - 11 Mbit/s
Range (Indoor)  - ~35m

Wifi G (802.11g)
Release Date - June 2003
Op. Frequency - 2.4 GHz
Data Rate (Typ) - 23 Mbit/s
Data Rate (Max) - 54 Mbit/s
Range (Indoor)  - ~35m

As you can see, the only difference in Wifi B and G is that the typical (average) data rate is higher in Wifi G. Can you even reach 4.5Mbit/s on a Malaysian ISP line? Think twice. As for the recieving range of P1i, it cannot be compared to a notebook. The range is ok and performs reasonably well.

it work ok on my phone but pc no only send data ok but no data recevied.