I have two other cars that I drive regularly. The Belta is covered up and I don't get time to drive it. I do however, start it up once a week take a short drive, check all the fluids, check the air in the tires and then park it back.
185/60/R15 would the best size to go for. It won't change your drive quality and won't harm your suspension.
As for alloy wheels, OEM's will be the best option. But everyone has their own choices.
Below are three different wheels that the Belta came with. The first wheel is a 14'' one and came in the 1.0L XS package. The second wheel came in the pre face-lift G package and the last wheel came in the post face-lift G and XL package, both of these are 15''s.
NOTE: All of these wheels were optional, expect for the 1.0L XS package and have a 4-bolt pattern.