Don't worry about the hops debris and trub going into the fermenter. If you want to use a strainer and pour through a strainer you can. but you don't have to, and it'll all compact down in the end with the yeast when the beer is finished.
Brewer's Best kits are extract kits, not partial mash kits. They are pretty good, with specialty grains for steeping and extract, and make a decent beer.
Broken Leg Brewery
Giving beer a leg to stand on since 2006