What I mean is if I'm 18 and dating a 16 year old what can't I do sexually? Like is it just Sexual intercourse or is it anythng that can give an orgasm lol... just a little confused on that part like its OK to finger and oral stuff like that just no "going all the way " ?

Best to leave "jail bait" alone. Essentially any sex act can get you in big trouble and not just going all the way - it's ANY kind of sex act whether you do it to her or she does it to you - you will be the one in big trouble not her. So don't even think about 16 year olds. Try dating over 18'ers instead and you won't have to look over your shoulder waiting for the law to catch up to you and arrest you.