1) I'm not sure what your asking by "How does it go?" Well you can go a couple ways about it. Someone (bass, drums, guitar, whoever) starts playing something then the others add to it, change, or play whatever fits in well. Just a regular jam session. OR since it will be your first time practicing together. What you could do is sit down with everyone else and decide on 3-5 songs to learn at home on your own. The next time you guys get together you play the songs BUT change it if you like (new guitar solo, different drum beat, ya know... just switch it up) just jam!
2) If you guys haven't even played together and you are worried about differing styles I would pump the brakes hard man. Don't worry about. I read somewhere a long time ago that said something like, "playing music by yourself all the time is like being a ravenous tiger with cotton dentures." If you aren't willing to sacrifice a little creative power to make room for the others, you won't cut it in just about any band. So don't make a fuss about personal style. You won't learn anything if you don't play with other personalities. Also, simple can be just as bad (or good) as complex. It's all about making music that is pleasant to listen to. Simplicity and complexity have nothing to do with the quality of music.
3) So you're asking how to manage your time? No one can really answer this question for you. You make time for the things you love and you cut out useless shit that wastes your time (ahem reddit). I don't want to come off as rude but if you live a good life you will always be busy with something. Music, school, job, girlfriend, etc. Time management is a life skill that takes practice and consistency. Bottom line is if you want to work, play music, study, and whatever, you will have to make time and be flexible to meet all of your goals.
4) Which comes more natural to you? Singing or playing guitar? Guitar came much more natural to me so what I did was keep playing the same bars over and over again nonstop. What I would do is then just start talking or having a conversation with a friend/roommate. Then my playing just became more of a white noise. After, start humming the melody while playing and then singing. Boom. Not easy at first but if you build it they will come.