I did a search to find out what a swift rasbora was. Discovered they are the Hengelis. I do wish they would stop coming up with different names! :evil:
These are great fish and I have them myself. They are also very suitable for the small tank you have. Did you check the ph etc of the water they came from before you acclimated them to the new tank?
The temperature will swing a few degrees and this is normal and not a problem.
Rasboras generally like a current, their torpedo shape makes them suited to faster moving water.