When using a plastic mini keg does the beer come out well and how many times can you re-use the plastic bottle's ?
Assuming that the plastic mini keg has been properly cleaned and sanitized, the beer should come out well.
I do not know any specific number of times that you can reuse it. You may need to replace seals after a few reuses, and depending on availability, it may just be easier to buy a new plastic mini keg. The mini keg itself shouldn't wear out though assuming you can keep the seals in good condition.