I agree with your sentiments regarding the pullup resistor - too low, too much current, too high succeptability to transients, personally I would usually put 10k in this instance as most of my stuff is mains powered.

As for the transistor theory - just goes to show how long it is since I've touched these devices! I didn't want to mention gain spread etc and complicate the issue too much - I did suggest Deepak do some reading though.

So if you see a transistor amplifier designed by me - don't touch it!!

I do wonder if Deepak is using a 6v rail for his relays - how is he regulating his 5v for the micro??