pdf view help

Hi
I have a couple questions on pdf view if that's OK...

1. I can see the pdf are stored in the templates_c folder and the link looks into here. Will these pdf's ever get removed from here (not sure how but worth asking) or just keep building up? Could end up quite large!
   
2. Instead of being put into this templates_c folder - could they be put somewhere else and with a specific file name depening on the record being viewed? eg invoice 1234
   Many thanks still to you all for fanstic product and support