Using a different modem will make a difference only if there is a problem with the modem. How is the service supplied? Are you getting a separate cable feed the same way as if you were in a single family house? Or is there one feed to the apartment bulding and all the renters are sharing that through a router or coax cables/splitters? If the latter, there's not much you can do. If the former, the service should be decent; what is the advertised bandwidth?
To use somebody else's unsecured (or secured) wireless network for internet access, which is illegal, you have to be willing to steal. Since forum rules forbid asking or offering help for illegal activities, I've already said enough.
To use somebody else's unsecured (or secured) wireless network for internet access, which is illegal, you have to be willing to steal. Since forum rules forbid asking or offering help for illegal activities, I've already said enough.