I am going to harvest some wild hops I found. Is there any way of determining the characteristics like alpha acid? I was thinking of maybe just using them for flavor/aroma/dry, since I have no idea what the contribution would be.
Your best bet is to use them for flavor and aroma, since then you can use them as is. If you wanted to use them for bittering you'd have to find some way of measuring the bittering acids, such as boiling in a light sugar solution for 30 mins, doing the same with another known AA variety and comparing/diluting until you can get some idea of the bitterness.
Quite a lot of work and guesswork, so best to play safe and use them for flavor and aroma. This is also where fresh hops really shine since they've not been processed, which causes dry hops to lose volatile oils. This makes fresh hops particularly suited to hopping in the secondary, aka, wet hopping.