While yes, I can kinda read your questions, 68% of hybridz is full of very wise, informative people that are blind as crap because they're 100+ years old. So you might want to increase the size of your font so people dont have to copy and paste it to enlarge it.
Creating a wider track rear suspension sounds like a project. I've read that you can mount/fab up a 240sx rear suspension onto a z and that will widen your rear track, so you might look into that. As for low offset wheels, Ill leave that to someone else as im not 100% sure on how Id go about answering that question. Hell, Ill try. Basically you cant run a 12 inch wide wheel unless you have like 18s-19s because you wont find decent streetable tires for them. So realistically your going to have to use a 15 or 16. They dont really make performance tires in these sizes super wide, so you'll probally be limited to a 8-9.5 inch width wheel. This only leaves you so much room to backspace before your at like -75 offset. I'm stopping here, hope to have given you some ideas. Ask for me to clarify if your confused.