both very inexpensive items, fine for just listening to audio, I would save a bit more for something a bit nicer.
Watts is power handling of a speaker or power supplied by an amplifier, best to match them.
Too much power from amp can result in damage to a speaker at high volume, too little power can lead to poor sound quality due to lack of control over the driver (also bad for speaker health). I'd rather have an over powered amp and be careful with the volume control.
Tweeters handle the high frequency information, so yes, they are important.>good enough for pleb use?
Not sure how to answer that, listen to them and make a judgement.