At age 18, is she healthy enough to run barrels still? Not saying she can't be, but I would have her checked by your vet, dentist, and chiron to get the okay to go ahead and do barrels with her. She may have arthritis issues, hock issues, or more.
As far as conformation, she is very toed out in her front legs, which can create excess stress. She also is slightly cow-hocked in her back legs, although not as bad as her front legs. She has a very steep shoulder angle, and slightly short neck and/or long back.
Not horrible, by any means. But of course, not perfect conformation.
It sounds like to me all you want to do is learn to barrel race at small local levels, which is fine. As long as your expectations are realistic to what you can attain with this horse. Obviously, she is not going to be NFR caliber. But that's okay, as long as you are okay with that.
∞•*˚ Βгįťţαňγ ˚*•∞
It is not enough to know how to ride; one must know how to fall.