Not really. Weed seeds are air-born and bird-deposited and will colonize any bare ground. You'll just have to keep after them.

Not all weed killers work the same way. Some will only kill off the top growth while others will be translocated to the root system and kill that off as well. The top growth only type is fine for annual weeds but perennial weeds - dandelions, dock, plantain, etc. - will simply regrow unless you kill off or remove the roots as well.

As for prevention.......not really possible :) As noted, weed seeds will be brought in via various methods. Using a pre-emergent like Preen can help to reduce significantly but not completely.