Hello
I commend you for asking these questions before you're little party this weekend.
As grace said you would be putting yourself at low risk for situations 1 through 4 in what you describe. By low risk we mean not to worry about it in the context of STDs.
But to answer your new question about what STDs you should worry about: they are (again it a low risk)
For situation
1) non-chlamydial, NGU, gonorrhea, herpes, syphilis.
2) anal gonorrhea, herpes, syphilis.
3) oral gonorrhea
4) Hep A and C, oral gonorrhea,
AGAIN, the chance of getting these is not zero, but it is rather low, very very low.
well understood about the protection part grace.
if in an event in future where i am tied in situation like the questions i posted what individual STD would I have to worry about? All?
all 4 of your questions are very low risk in general. we recommend protected sex and protected oral because it works to protect yourself. if this is a partner who's status you aren't sure of, it should always be protected contact, even for relatively low risk encounters to best protect yourself and save yourself worry and testing :)
grace