Welcome to the SS club:)
I ain't no professional so yeah.
The 150 Rs filter fits all Suzukis and is a bit smaller in size. The original Japanese one 950 Rs is purely made for Swift. I just use the Guard one since I get my oil changed at 5000 km and yes I do use Liqui Moly!
And for extended warranty, I think you can get warranty for 3 years Or 50/60,000 km which ever comes first. I think it costs 9000 rupees etc or something, and that is something I would go for.
Funny thing, I don't even know what my warranty covers lol:P
Hope an expert can correct me/ add some more useful info ^_^