Not to alarm you, but I think bleach only kills the HIV virus, and not the Hepatitis C virus.
No one can really tell you the chances of you having caught it or not, just get tested at the right time.
Re-using other people's needles is a really bad idea. You should buy them over the counter, or go to a needle exchange program. If you can't do either one of those because you don't have an exchange program in your state, and the pharmacists are being bitchy to you, buy them online.
Please don't re-use other people's insulin syringes.
Depending on what you use, a small bump may mean you missed, or it might be a reaction to pulling the needle out too soon after the injection is done, or it might be a reaction to the product or the cut in the product you're shooting.
There's no benefit for tying off, unless you can't see and feel your veins. In that case the benefit is being able to see and feel your veins.