For peppers, the riper the hotter.
For the sauce to keep you'll need to keep the pH below 4, fairly acidic. Most sauces contain vinegar for this reason. You can experiment with different vinegars, lemon juice, lime juice, etc. Of course this will also effect the sauce's consistency, as will temperature. So if you are cooking your sauce in a pot, and you like the consistency, it will be a bit thicker once cooled and bottled.
I started growing peppers for the purpose of sauce making but haven't made any since before xmas 2010.
There are many ways to make hot sauce, some people add fruit or carrots, others like only peppers. Some people age and ferment their peppers before making the sauce. I loved fermented, pure pepper sauces the most. I have few threads in the sauce making section of thehotpepper.com,
http://www.thehotpepper.com/forum/91-hot-sauce-making/. There's some good reading and sauce ideas there.
I'll give you the rundown on a basic sauce.
Destem and clean your peppers. Cutting out the core / placenta / seeds it optional but most of the heat is there. I prefer to leave it all in. You may want to add onion or garlic (I like to add onion or shallots). Add the ingredients to a pot, simmer with some vinegar and canning or kosher salt (ie: no iodine). Cook until the peppers are nice and soft. Transfer to a blender and blend until desired consistency. Transfer back to the pot and simmer some more, adding vinegar or water (I don't recommend adding much water).
Make sure your bottles are clean and sterile, much like your brewing equipment. Sometimes I hot water bath then keep my bottles in the oven until I bottle. Transfer your sauce to the bottle(s) and invert them so the heat and pH of the sauce kills any bacteria on the lid. If you have plastic tops do not hot water bath or pressure can the filled bottle.
Here's some of my threads there:
http://www.thehotpepper.com/topic/12675 ... out-great/
http://www.thehotpepper.com/topic/11380 ... hot-sauce/
http://www.thehotpepper.com/topic/11528 ... l-29-2009/
Good luck!
-Rob