It will be a tight fit and will need prising out with a bar of some sort.
Have a look here
You can see the mounting on here, once the top is loose, you should be able to move it towards the engine and get the belt off.
Then you just remove the lowr bolt and take it out. You may have to wiggl and manover it to get it out but it only should take 15 min.
Yes that is right. The star shaped nut is a T18 or T20 i think, but you should be able to get it with a normal hex socket, try a 14MM.
Yes the tensioner is sprng loaded and you will be able to get the belt off with that, i would remove the belt before undoing the alternator.