Ok, so regarding focal length. My suggestion would be to take the lens you have currently (I'm assuming it's something like an 18-55 or something similar) to some of the venues you want to photograph and take some pictures.
They don't have to be fantastic, they are just for reference. It will help you decide for yourself what focal lengths you really need to get the kind of shots you want. If your shots seem like the FOV is too narrow and you can't back up any further, then maybe an UWA (ultra wide angle) lens will be a good option.
If you find that something in 18mm is wide enough, then you can save yourself a lot of money because the UWA lenses are generally more expensive. Also your looking at a choice of zooms or primes, so if it were me I'd set your current lens at 35mm and leave it there, take some shots that way. Then do the same at 50. See which focal length gives you the results you want most often.
If you think a set focal length like 35mm or 50mm would do the trick a good fast 1.8 prime would be fairly inexpensive and produce some good results.
If you think after doing some test shooting that the fixed focal length might be too limiting and you'd prefer a zoom, perhaps something like a Tamron 17-50 2.8 would be a good investment. It will be more flexible than the prime however it won't be quite as fast.