Regarding body language; Personally, I think I maintain too much eye contact, but that's because I lip-read and stuff. I know, lips and eyes are different but.. too long to explain.
I think showing that you're following the conversation by nodding and smiling -- and just simply grunts of yes/no will show the partner talker that you aren't pretending to play tetris with the chairs in the room in your BRAIN.
Being weird is good. Weird just means different, or unusual, and who the fuck wants to be usual? Just don't define yourself as weird because, frankly, it's a very all-engrossing term that does nothing to depict who you are.
People can get used to the 'air of not looking like you care what they're saying' if you can actually show that you do care what they're saying with your response. by listening to what they verbally italicise and enunciate (that's not a link lol) you can focus on what it is that they specifically want to elaborate on, and either probe further with questions or provide your own associated annecdotes.
If you feel that you have a monotone voice then no doubt you will either exaggerate with ott gestures of with occasional, sporadic tonal fluctuations in your voice. Again, people may take a while to get used to that but provided you are an interesting person (as you are) and that you are talking to them for reasons beyond talking about yourself (as you ought to) then they will overlook that. When you go to uni you'll meet a wide range of people that are all new-born, too, who will be judging you just as much as they are scared of being judged by you. Just find confidence in yourself (which I'd be surprised if you lacked any, for you know this forum loves you) and what you say.
Also in regards to the monotone voice; that might also just stem from your fear of sounding boring-- you're practically 'listening' to their silent reaction more than you're concentrating on making your talk interesting. It should come naturally, but if you don't feel settled then it won't. To get around that... well it's hard to say. People will be more attentive and less distracted by your tone when you are talking about them, and again tonal EMPHASIS on key phrases/words will keep their attention focused.
Cultural references, I find, are like in-jokes. If you haven't established that the person you are talking to is a simpsons fan then shouting out a probably-obscure reference will either make no sense at all, or make them feel stupid for not knowing the reference, or make you seem obsessed by the simpsons :P Verbalising an obsession in that way only tells the person that you are obsessive, and the obsession matters not, but that's another thing.
Your definition of 'giving' in a conversation is different to mine, I think. You assign 'giving' to be somewhat of a sacrificial term; not lending someone some information but giving it away, as if what happens to it is totally out of your control. For sure, you shouldn't 'give' everything away, but you shouldn't feel like every detail of your life is seriously worth all that much because truth be told, it's not. Most poeple are obsessed about their own lives. it is perhaps polite to also share about your life in order to show the other person that their life is worth something... if you see what I mean? Like, someone tells you a secret then tell them one back to show them that you are trustworthy? I dunno if that makes sense.
This is a long post, again, and that's annoying.
C_B; college for me was one thing, for you it's another. People are, generally, very strange. University provides another level of challenges, and while daunting I think so long as you just remember that you aren't the only person in the conversation, I think you'll do fine. At uni you discover more about yourself than anyone else.
EDIT: As a two-hour-later footnote... Er, yeah;
Recognising and mobilising upon the participating speaker's dialect/register is very useful. I mean, if a guy says "dude" or "man" all teh time, then repeating these utterances when replying/spurring a new conversation will make them more at ease. Knowing whether the person you are speaking to is going understand long words or not helps, too. I mean... if you listen to how someone talks then you know how they talk. people find it easier to listen to vocabulary that is similar to theirs. Like, I mean, saying "mate" instead of "bruv" or "dude", but expanding from just identifying how they like to be addressed. Length of sentances, whether they focus heavier on nouns or adjectives or whatever... discussing these theories behind conversations is a lot more complicated than what actually goes on. Half of this occurs naturally, subconsciously, unknowingly anyway!
There's no direct point; I just highly recommend that at any time someone says something to you, you say something back. That's the easiest way to enter a conversation. As for holding it? Each to his own.