Here's a link that may shed some light on the subject...
http://www.thinkerf.com/Downloads/SawTooth.PDF
Personally, I always try to use the lowest TPI I can to accomplish the job. A 4 TPI blade is much more aggressive than a 10 TPI blade, as an example, and will cut much faster in many cases. As CNC Dan pointed out, you'll need to keep a certain number of teeth engaged with the material to make a smooth cut, one the won't 'bounce' the blade and break the teeth off or mar the workpiece. For instance, when you're cutting sheet metal on edge you'll want a very high TPI.
I have three bandsaws plus a handheld one I use for metal only. Two of the standups are used for wood, and one is used strickly for cutting aluminum. They all have different blades because different work requires different TPI blades as well as how thick (tooth to back of the blade) the blades need to be. A three quarter inch blade is inherently more stable than a quarter inch blade, but it can't handle a tighter curve radius like the quarter inch thick blade can.
The width of the cut is called the kerf, and you want that to be as thin as you can, and since the blade manufacturers dictate how thick the blades are side to side you have no control over that, anyway. But you do have a choice of the TPI and the front to back dimension when you choose a blade. Basically the lower the TPI the thicker you want the blade stock to be within reason.
So when you go to buy blades be sure to get a couple different sizes to handle the different jobs. And when cutting aluminum watch out for galling that can break a tooth or five off the blade and bury them in the metal piece you're cutting. Because as the other teeth on the blade run over the hardened teeth that become imbedded in the aluminum they wear down almost instantaniously destroying the blade.
As far as speed goes, the alloy of the metal will determine the best speed (fpm) and I'll adjust my speed control as much by ear as by sight. Speed creates heat and heat kills. The horsepower of your machine will also come into play with speeds, so a chart may give rates for an optimal situation where your experience will tell you what's really up. HTH.