If you upgrade to premium then you will be able to upload in most boards, have a longer edit time and be able to see hidden boards that you cannot see now. You also get access to certain things / more FP.
GMaster status allows you to close / open your own threads in Member Wars to prevent players from posting. You will also be able to upload your images as usual. Its up to JB's discretion but he also highlights your game threads so they're unique.
Deleting and editing other people's posts is a moderation group position and is never associated with premium or GMaster status. If you are donating just to be able to delete then you will need to rethink that as only JB awards moderator positions. If you come across member posts that you think needs to be dealt with then please use the report button or post it here in your intro and one of us will take care of it when we can.