Whats the best way to clean up the altenator and fuel rails, etc. ?

 

I get a roll of blue shop towels (its like a roll of paper towles) wipe everything down then take a mild engine cleaner spray it on the towel and start cleaning all the little spots, tooth brushes help out a lot. I do this and it works great and I make pretty good money with it, I also spray meguiers hot shine on SOME of the hoses and rubber lines

 

Is it okay to spray degreasers (like for example simple green) on the engine directly? As long as I keep it away from the opti I guess? What about the underside of the hood? Will it ruin the paint?

 

on the engine, simple green is fine
about the paint...
you gotta make sure it doesn't sit on there too long and it would probably help to dilute it before you did it
you could possibly damage the paint if it sits too long or if it's not really diluted, but if you're careful about it, you should be fine