i'm getting my lip pierced for my birthday but have a few questions.

what length is the initial jewellery(i want to get a labret stud on the left side) likely to be?
will i have to change down to a smaller length after swelling goes down?
how long would i be able to leave it out for without the hole closing(obv after initial healing) as my nan hates lip piercings so i would have to remove it when i visit her- OR if i fitted a retainer like the push fit bioflex ones sold on here how visible are the clear ends you can get to put on them?
does it get in the way or hurt when kissing, eating and say brushing your teeth

sorry if these seem realy dumb questions