Yea im not a track genious and I am sure a few more people in here will give you some pointers. The RT thing will get better and your launches will get smoother over time. I wouldnt really try to rev the RPMs much and try to dump the clutch unless youre trying to do a burn out like you stated.
http://www.the370z.com/brakes-suspen...on-thread.html
That might help a little bit and give you some other ideas. Few people said the windshield washer fluid alone is about 8 pounds. HaHa... But practice makes perfect. I know a few people on here said they were running 13.3s which isnt too far off from where you are. A little tweaking and I am sure you will be right around 13.5 before you start modding your Z.