I currently shoot a 29 inch draw with no string loop. I have heard of many advantages to adding a string loop. If I do so do I need to adjust my cam to a 28.5 in order to keep my anchor point the same?

You might but im not really sure because i have never shot without one so im not much of a help, maybe someone else knows. Sorry.

BB90

The only thing adding a loop will change is the distance from your string to your release hand. If your release has a adjustment on it you can make it shorter to maintain the same anchor point. If not you anchor point will be a little furthur back than what you are use to.
Sometimes you just have to try a few things and see what works the best for you. For instance if you like the string to just touch your nose and you shorten your draw length it will no longer touch. You also need to be careful not to make up for any changes by moving your head or changing your form...

Remember with archery always adjust your equipment to fit you, never adjust you to fit your equipment.