Hi need some info if possible.

I want to be able to do green screen from photos.
What is the best software to do this with.

I have a PC and and an IMAC

I know about taking photos and using photoshop to remove the green but there must be an easier way esp for 2 computer formats.
I use my Imac for all my photography so what software is the best for removing green screen and allowing me to add in my own backgounds.

Is there any software which will allow me to shoot live by connecting my camera to my imac (canon 6000 i think) so its a decent dslr.

Any help on this would be apprecited.