I used glutes for a total of 3 times after that it was quads, which I liked alot better. Now I use quads, bi's, and tri's. I'll probably never use glutes again because its just to akward and the other spots are much eaiser.
lol! No aspirating is when you pull back on the plunger to make sure your not in a vein. If you see blood when you pull back then take the needle out and find another spot to inject.
Yeah its fine. Its a vacum because their is no air in the muscle and I bet when that happens to you you notice its really hard to pull back on the plunger. If your in a vein the blood will flow in very easily.