offbrand companies have fake power ratings
offbrand companies have poor quality materials
offbrand companies have higher distortion levels

just a few important places they lack.

ya pyle,boss,jensen,lanzar,visionik and many more are bad brands. the easiest way to know for sure if the ratings are correct is checking if its cea-2006 compliant.

different kinds of crossovers. your polk crossovers split up the frequencies for each of your speaks individually. your tweeter will get high stuff and your midrange will get the rest. the amps crossover just lets you set a general frequency spectrum that doesn't care what its sent to. without both of the crossovers your tweeters would attempt to play low frequencies its not designed for.

ya wire will go from the speakers to the crossovers then to the amp.

that amp i linked bridged will be 100watts per speaker so it should be perfect for you. it needs an 4 or 8 gauge wiring kit which will probably be around $20.

you'll wire it kind of like this except this doesn't show your tweeter+crossovers.

just use the outside pairs exactly how that picture shows. most amps only allow for that wiring configuration.