French Questions regarding expenses, living costs, ed?

Can I live on campus (uni) during my stay in France (for studying)? Is it safe? Which one is better: living at uni or renting a studio in a French suburb? Which one is more expensive?
Which city is cheaper to live in(in terms of accomodation, food, daily expenses)- Bordeaux/Lyon/Poitier?
Which is a cheaper form of transportation if I want to travel to other European countries: train/ plane/ car or bus (non-private)?
Is it cheaper to travel around europe if you are a student?
How long can I survive on 4000 euros- without travelling expenses but with daily expenses?
Is it hard to find a casual job in France if you are an international student and can only understand like 60% of french, 80% of written french?
Thank you...

I can only answer part of your questions, not being French nor a uni-student.

Traveling by bus and train will be cheaper when you are not yet 26, or have a students ID, and the cheapest option is the bus for short and mid distance, flying long distance if you book ahead.
But bus travel is not considered comfortable and longer distances are mostly done overnight.
If a few fellow students share a car it might be the cheapest option, but owning a car is really expensive and petrol is expensive too.

4000 euro is not a lot, for daily life when going to university it might last 100 days if you also have to pay for your accommodation, traveling 40 days is more likely, although a lot of people manage to use less a day.

Mostly it is safer to live at the campus, but I am not sure for the towns you name, never been there.

You might get better responses if you repost this question in the travel - France section, or in the education and reverence - studying abroad section.