Spider bites generally cause massave uncontrolable erections. the only way to make the boner go away is to punch your penis.
The brown recluse is found there. Some staph infections also mimic a recluse spider bite as well. Yes, that is the mechanism of injury for all spider venom. Since they can't chew, they inject...
Unclean house causes spiders.
Peter has been bitten by an ordinary spider which is attacked by radioactive force
In the comics he is at least 15 years old when he gets bitten.