TeX system for Macintosh, recommendations

I'm using Emacs (Aquamacs) for working with LaTeX on MacOS X and AUCteX is really great, but you seem to look for another alternative.

Did you already check the comprehensive list of LaTeX editors? LaTeX Editors/IDEs

The answers there also describe their features and advantages, so it's very interesting and a really really long list.

For MacOS X available are e. g. (in the order of upvotes)

• TeXMaker
• TexStudio
• TeXworks
• Kile
• and many other multi platform editors...

Exclusively for MacOS X, there's

• TeXShop (Free)
• TextMate (commercial)
• Latexian (commercial)
• Technicle (free)
• Archimedes (commercial)
• ...

I'm sorry, I can not comment on your TEXINPUTS question, as I do use only one such setting up to now.