Don't think I've heard of too many problems with the MK7 to be honest, not in 1.6 form at least. They seem fairly reliable.

No turbo kits available that I know. I believe the ST engine is related to the 1.6 Sigma in your car, so that would be the easiest route but, honestly, if you want a turbocharged Fiesta, just buy an ST. Converting yours will cost more than it would cost to buy an ST by the time you take in the purchase price of your car!