This has been done before, and a write up about it, with photos posted in the "HOW TO" section. All of your questions are answered there. Check it out. BTW, I've done a 16v turbo and am still running it after 3 years now. Do yourself a favor and do it right the first time, don't cheap out on components, and build it for relibility.
Just to answer your questions quickly:
1. The 16v engine is better suited to turbocharging because of the multi port fuel injection. Max safe boost on a stock engine is 5/6 lbs.
2. The injectors should be fine, I run bigger ones, but others have used the stock ones providing they're in good shape. You might want to add a manual fuel pressure regulator to up the pressure a bit.
3. If you don't have air conditioning, or don't plan to use it, the whole job will be much easier. You can easily fit a air to air cooler in front of the radiator without the ac condenser in the way, and the manifold for the turbo will be much easier to build as well without the ac compresser installed. Air to liquid intercooling is much more consistant, but a more complicated install.
4. YES, you do need a turbo manifold. Don't cheap out, build a good one. If you can "kinda weld" better off letting someone who knows what there doing weld it up. Use at least steel weld el's, better yet stainless steel for longevity and better heat retention.
5. You don't need a Mega Squirt with the 16v engine, the stock ecu ccan compensate up to about 5/6 lbs of boost.
6. Good luck and happy boosting.