Din,

(i) In order to aerate the bio-filter, what brand of blower is considered reliable and not noisy. I've been adviced of this brand called Hi-Blower but is there a certain rated capacity that I should get ie Hi Blower 40 or 80?
Its actually called Hi-Blow. Get the 80, there is always room for improvement. The more air the better
(ii) How much do these blowers cost and where is a good place to get it at a reasonable price in Kuala Lumpur where I live?
I'm not sure coz I'm not local. Here in Sydney they are about $400AUD.
(iii) Since I'll also be adding some new mats in the chamber, what should I do in order to maintain the existing good bacteria in my existing mats and also to ensure I'll grow new good bacteria in the new mats quickly without compromising on my current water parameters?
Get you new media clean, cut and ready before removing your existing media. Add the new media in between old once. It shouldn't compromise your water parameters unless you have issues already. Also try to do this in low humid mild day.

Good luck.