importance of phono cartridge

AT the risk of sounding like I'm talking down to you, I have to say: nothing in the system will replace what a lesser quality cartridge did not retrieve from the LP. The closer a piece of gear is to the source the more it will affect the sound since the rest of the system magnifies what took place earlier, while adding it's own signature.

Start at the source and work your way to the speakers. This will result in the most satisfying musical experience.

A good cartridge will sound better in a very good tonearm than a very good cartridge in a good tonearm.
:-)

Yes and yes, IMO. On the other hand, I feel it's more cost effective to put the money into a good/great TT. You can always upgrade the cartridge when you're able, plus there are many moderately priced cartridges that will give you 80% of the performance of the most expensive ones, expecially when installed in a better TT/tonearm.