1.For X10 version only.
2.Yes
3.Bloom,Depth of Field,Hue/Saturation,Filmgrain,Sepia,Cartoon.
4.Not quite sure what exactly is it that you want.Like a portal whole that sees into the other parts?If so,no.
5.Yes.You can create terrains with a modeling program and import them into the Engine.
6.The only thing you can do to speed it up is not clog it up with unnecessary entities.You can also use a speed optimizing mod.
7.Look at the Best of the Best thread.

PC Specs:Windows 7 Ultimate 64-bit,Intel Core i7 960 @ 3.20GHz,NVIDIA GeForce GTX 480,12GB RAM,2x Western Digital 997GB HDD