Bathing Should I use a dryer after bathing???

Depends on how thich their coat is, as very thick coat has a tendency to lock in moisture which could cause fungus & other skin issues.
I ony use a dryer on my peruvian during winter, but it is a lot more stressful & I prefer to avoid bathing her in those colder months. It does take a long time to get them fully dry, and you need to make sure they are before putting them back in the cage. Swich towel a few times to make them dry faster.

If you use a dryer, make sure to keep your fingers in between the dryer and pig to avoid the little one getting burned & use the cold setting. But I see no reason for this if you only wash their bum.