All your problems just reinforces why I left vinyl behind. I suggest you cut your losses and move on to quality digital equipment :)
Thinking back about 20 years (last time I played a record) I bet your cartridge is misaligned. This can cause distortion during loud passages. Sorry, don't recall the steps of alignment. Sure you can google it. Regarding the woofers moving and the snap crackle pop: yep that's the magic of vinyl alright :) Probably a really deep cleaning could reduce the snap, crackle, and pop. But my experience is you just have to get used to it. Think of it as the charm of vinyl. Kind of like snow on TV picture via an antenna, multipath on FM stereo, and fading on AM radio. The woofers moving was typically resolved with a subsonic filter. All the receivers of the day had them. Probably can't find one of those anymore so just enjoy the power robbing show (and don't turn it up to high!).
Thinking back about 20 years (last time I played a record) I bet your cartridge is misaligned. This can cause distortion during loud passages. Sorry, don't recall the steps of alignment. Sure you can google it. Regarding the woofers moving and the snap crackle pop: yep that's the magic of vinyl alright :) Probably a really deep cleaning could reduce the snap, crackle, and pop. But my experience is you just have to get used to it. Think of it as the charm of vinyl. Kind of like snow on TV picture via an antenna, multipath on FM stereo, and fading on AM radio. The woofers moving was typically resolved with a subsonic filter. All the receivers of the day had them. Probably can't find one of those anymore so just enjoy the power robbing show (and don't turn it up to high!).