I use this answer a while with other qustion maybe it can help you too/two :-)
1) Ai file is absolutely perfect. -Use CYMK colors
2)Pantone is OK It is more reliable. This way you are on the same page with the printer. What pantone color you see on your monitor and what pantone they will see or use in printing.
3)Gradients are ok especially if you give them you full vector. NOT in PDF form because it will be chopped chopped into lines. this also apply in dropshadows.
4) EPS is also ok with your color settings.
5) DPI setting is printers job. You dont have to worry. Just set your resolution in 300ppi. Make sure you give them also the Edittable files for JPEGS PNG or PSD FIles. Just embed them first in illustrator If they want to make it more clear atleast they have the raw files.
6) The Higher resolution the better. But too high because it will have big file size and the prepress will open and close it in slow speed. 300-350 ppi is my recommended settings.
7) a) Outline ALL your texts if possible. It will be the BEST help you can give for the Prepress person. It is ok for the Generic fonts like Arial but in some special font you better it will be in outline form because it is already set. b) If you want it Edittable Just keep your a personal copy/backup or GIVE all the fonts (.ttf or softcopy) you use in the artwork.
8) As mentioned PMS or Pantone Matching System is Good because it will as accurate as sharing same monitor to them. We can see it in Pantone colors perfectly if it is in Vector file e.g. AI,PDF, EPS, SVG, .CDR
9) If your affraid for the copyright issue (which i personally Do when designing materials). Set aside it. Prepress people are too busy to copy all files. We appreciate more if you trust us. If we see your artwork is beautiful and Perfectly done,we will try our best to make the print out the best way as you see it. Seeing your good artwork printed good will be our reward as Prepress designers.