Bearing in mind that I have less than an hour of play time under my belt (plus too many hours of reading stuff online while at work)...
So 'supercruise' analogous to eve 'in warp'?
Except that you can change direction, accelerate and decelerate as desired. Rather than picking a location and pressing buttan, you get up to supercruise and then fly around at speeds ranging from (iirc) 30 km/s to 300c. Those high speeds allow you get to the outer edges of a system, which may be as much as 200,000 LS (light seconds, unit of measure used for stuff that's really far away) in as little as 20 minutes (which is still a fairly dull way to spend 20 minutes).
If they are going so fast how do you, uh, detect them and match their vector? Is all supercruise the 'same' high speed or do some ships 'warp' faster?
Speed in SC is controlled by throttle input. As far as I know, all ships have the same max SC speed and accelerate and decelerate at about the same rate. So catching someone who is already at max speed is just about impossible, but over short trips, people usually aren't going max speed. This is because you have to decelerate to drop back out of SC without taking damage, and it's really really easy to overshoot your target if you don't slow down early.
So if you want to catch up to someone, it is possible. You just need to be willing to go faster than they are and try not to overshoot. If someone is already at max speed, however, you are most likely out of luck. You will need to wait until they start slowing down before you can catch up, and then you'll need to decelerate as well in order to get behind them without overshooting.
Is there an anti interdiction module?
Nope. When interdicted, you get an alert that it's happening and then an escape vector appears on your screen. You do your best to point the nose of your ship toward that escape vector, and if you are successful, you stay in SC.
Are giant beefy slow ships harder to dodge the interdiction? Can a tiny ship interdict some huge capital ship?
I have no idea. I would expect that nimbler ships will have better luck with interdiction, both as aggressor and target, but I can't say for certain. It wouldn't make much sense for that not to be the case given that success is based on maneuvering.
No idea about interdicting capitals, so far I don't think anyone has ever seen one in supercruise.
I think we're all still waiting on more info about how travel will work in star citizen. I'm just glad to have another space game to tide me over while I keep waiting for that one.