I tested negative for HIV with the at home oraquick test 10 months after a possible exposure. Can I take this as a 100% negative result? Would like to stop worrying about this.

Not clear. No test is 100 % accurate. Get a pcr blood test to be sure.
Depends. Hiv test can be negative for several weeks after exposure. Therefore it is recommended that you repeat the HIV test about 6 months after exposure. If negative, repeat it after one year because some patients develop antibodies after long time. There are also tests available that detect the virus (antigen). Talk to your physician about it.