It's hard to tell what his motives here are, and other answers have addressed several possibilities already. I just wanted to add my perspective as a fellow woman (FWIW, CS department in US) who's had to deal with awkward peers before. My suggestions, in escalating order:
This means you doing work to minimize his opportunities for creating uncomfortable situations. Carry your papers in a plain folder so he can't see them, work in your office or with your back against a wall so he can't read over your shoulder. If he corners you in the hallway, make up an excuse to exit the conversation. (I used this one a lot when students would try to keep me after office hours...)
As an example, I have a rather large "personal space" radius, and I realize that's really my problem rather than anyone else's. So my tactic was to position myself across the table, in a single chair rather than bench, etc., to provide a natural barrier without having to ask someone else to change their (reasonable) behavior.
He is acting inappropriately, so make him do the work. Possible motives for his behavior can be categorized as, roughly, real academic interest but poor social skills, or just wants to bother you (for whatever reason).
To handle the first, make him show that he is seriously interested in your work. For example: "What are each of the papers you are reading?" "Right now, X. Say, you seem to be awfully interested in what I'm doing, maybe you should talk to your PI about collaborating with my group?" or "You know, there's a reading group for X, maybe you'd be interested in joining.", etc. This gives him a way to keep up on the research, without you being the unwilling mediator.
For the second, take control of the conversation. When he tries to read over your shoulder, close your laptop lid and say "Can I help you?" (or the milder, "Hey X, what's up."). Throw in an "I'm really swamped right now" to signal that you're not interested in an extended chat. If you're feeling nice, invite him to email you his questions and you'll respond later when you have time. Hopefully he will get the idea. Again, this leaves him an avenue for collaboration, without you getting cornered in a conversation you don't want to have.
Some people have very poor social skills and do not pick up on hints, verbal or otherwise. If he still doesn't get it, be blunt. It will feel uncomfortable and like you're being terribly rude but... behaviors like craning his neck to see what you're carrying around or reading over your shoulder are rude. (Here's a quick sanity check: do you see other people in your department acting like this? No? Then his cultural background is not an excuse, and he shouldn't be doing it either.) It is okay to be blunt in response, especially if he is ignoring what you think are obvious signals. I think Daniel Wessel's answer has some good advice on what to say if it gets to this point, so I won't repeat it here.