Why does my boyfriend never call or text me?

I've been seeing this guy since Septemberish (we met in late August) and we made things official about a month ago. Lately he hasn't been calling or texting me much. He has emailed me a few times but they are hollow emails. When we are together, things seem to be pretty good.

It also kind of bothers me because I haven't seen him since Wed and I'm not going to see him again until Tuesday (he has finals).

I'm not totally unreasonable, I know that finals time is a difficult, stressful time. I guess that could be why he hasn't been calling me much but I feel like he wasn't contacting me really even before finals started.

Also, here is some background info on what's been going on lately:

Last weekend, we spent the entire weekend together. Friday-Sunday. Overall I guess it was pretty good. I'm always unsure of these things. We didn't do much, just a quiet, rainy weekend in his apartment. He told me that sometimes he preferred just hanging out with me doing nothing as opposed to going out and such.

When I left Monday morning, he asked me when we would be together again and, since he has finals, I said I didn't know and that it was really up to him. I did offer that we could wait until the bulk of his exams were done. First he said that he didn't like that idea. Then on Wed night, he said that waiting a week was probably best. I have a lot of stuff at his apartment (including my laptop) so I asked if I could stop by briefly before that so I could pick it up. He said yes and that he wanted to hang out a bit because he was going to miss me a lot if he wasn't going to see me for almost a week.

So this is a four part question:

1) Would a boyfriend not call his girlfriend for reasons other than he doesn't like her anymore or he's swamped with work? Are there guys out there who still don't call or text even when in a relationship? Why is that?

2) Should I do anything about it? A long time ago, I would just call a guy but now I'm sort of guarded when it comes to this stuff. But should I even text/call him at all or just wait for him? I don't want to pester him or to think that he needs to give me 24/7 attention (regardless of what this question might indicate to you, I really don't require it, I just get nervous sometimes). But I also don't want to be too distant. Finding balance in these situations is a problem for me.

3) I know I should probably give him space but I'm afraid that if I do, he will find that he doesn't really like me. So how does it work, if a girlfriend makes herself a little less available does absence make the heart grow fonder or is out of sight out of mind?

4) Is it possible that he is losing interest in me? Is it probable? How quickly do men lose interest? My gut reaction is to prepare myself for heart break but I am also naturally paranoid and I am also really emotionally invested in this kid - which makes me 374683746% more scared and ready to run than usual.

Please, I feel really uneasy about this and I feel like I'm going to throw up from it.