TL;DR: you are not a relay neither an exit node by default!
[...] other people traffic pass through my network [...]
only if you configured your "Tor-software" to be an relay.
and even if so, that traffic is encrypted... else every relay (also the others through which your traffic is going) would be able to read and analyze the traffic which should be anonymized.
[...] if someone is doing shady stuff i can look like it's coming from me?
only if you configured your "Tor-software" to be an exit node (= the last relay, from which the Tor-network is left and the "normal traffic" seems to come from).
btw: so whenever possible, use
.onion-sites! it is more safe and reduces the load for the exit nodes.
I use [...] vpn is that good enough to stop hackers and such?
No. a VPN has hardly to do anything with (additional) security, it just redirects your traffic.
and even for anonymity you have to thrust the promises (if there is any no-logs policy at all), skills and software of one single VPN-provider.
providing a relay usually can/does not effect your security at all in a bad way; it would rather be a good idea to add "white noise" for avoiding time-based correlation and other guesses (especially as long as you are the only one using Tor from this internet access and/or not using Tor all the time).
additionally you'll help out and strengthen the Tor-network with providing some resources (bandwidth)... so every Tor-user should consider running a relay: https://trac.torproject.org/projects/tor/wiki/TorRelayGuide