Hi

1) It's more important what kind of surgery you want.If you want to lift the existing pre-maxillary implant it won't be removed but augmented. Or you can have it removed and have a new one put in.
2) During pre-maxillay augmentation a muscle called superior labii is lifted and put back. That muscle lifts the lips so if you get the surgery done your lips won't get lifted up for about 3 weeks. It will be weird like a fox's mouth. However after 3-4 weeks it will recover completely. The muscle won't get cut.
3) Pre-maxillary implant is very common around here but removing it is rare. Experience is necessary like any other surgery.