You will discover many things when living with you GF, first and foremost WOMEN ARE HUMAN. You will see her at her worst, and also at her best. If you just use some common courtesy then it will work out.
1: Go ahead and put the seat down. it is a lot easier than fighting about it
2: When shaving, wash the sink out. Also, put your bathroom stuff in a drawer, give her as much counter space as possible.
3: Do unexpected things. A single rose brought home will do wonders for your relationship.
4: If you want blankets (when sleeping at night), best thing to do is get ones that are usually 1 size bigger than you need. that way tou both stay covered during the night and you will not have a tug of war going on.
5: take some time to get used to sleeping together.
6: Just because you want IT, does not mena she is always ready for IT, Some of the best nights I have spent with my wife have been just lying in bed snuggling. It makes for better communication and bonding.
7: And last, but not least, TALK, and also LISTEN, So many issues can be worked out with simple communication.