I was wondering does it run well on a mac?

It'll depend a little bit on exactly what kind of Mac you've got... But it'll run. Maybe not well, but it'll run.

Generally you can expect slightly poorer performance on a Mac, compared to a PC. But it should certainly be playable.

Is starting out difficult or not?

It can be. EVE is a genuine sandbox, and that kind of directionless freedom can be overwhelming. It can also be intimidating and discouraging to look at the skill list and see things that take actual months to train.

The trick is not to wait - to just get out there and do something. You'll always have some skill training, some ship you're aiming for, some distant goal in mind... But that doesn't mean you can't play right now. Just get out there and do something.

What are the restrictions within the game?

There's a nice chart here that outlines all the stuff you can do in EVE.

You can shoot at NPC spaceships... Shoot at other players' spaceships... Build stuff... Harvest stuff... Buy and sell stuff... The thing is, EVE is almost-entirely player-driven. CCP kind of sets the stage, but the game is what it is due to the other players. It's really just a matter of figuring out what part you want to play.

I'd recommend finding a good corporation. Even if you aren't interested in PvP or anything like that, you still want somebody else on your side. Someone who can help you learn the ropes. EVE University is a decent place to start. They'll certainly help you get your feet under you. But you'll want to find something else after you've figured out what you want to do in the game.

The thing is... EVE is less of a "game" and more of a "hobby". What really makes EVE so interesting is the amazing metagame that surrounds it. All sorts of blogs and podcasts... Player get-togethers... The constant, ongoing swirl of propaganda and espionage and politics... So I'd strongly recommend checking out TotalEVE