Hello,
would like to ask do you use a sniper for Ebay, if yes, what sniper?
Are there snipers for other auctions, like delcampe?

http://www.jbidwatcher.com/

Totally free & works well.

I wonder is any difference between free and payable snipers in placing bid's speed? I. e. is 5 seconds enough?

I'm happy to risk it rather than pay another % or fixed fee to the snipping people. 5 seconds is probably too short anyway to be honest.