1) yes, and IMHO, it makes a 'more than subtle' improvement, not only when changing the regular zip cord to a shielded cable. I've heard 'BIG' differences between different cables costing (both costing the same, as varying prices...)

2) yes. definately. The most noticable improvement was when I wallmounted my tt, and put spikes underneath it. Upcoming will be spikes for the speakers, and a new rack.

3) Yes, but more subtle, I believe that a power cord can 'complete' the effect, when combined with a filter/regenerator.

4) YES. of course, the record quality eventually makes the biggest difference, but the source is what reads that, if you got a bad source, you have bad sound. No matter how good the recording can be.

5) Sometimes, yes, I think...

Keep them spinning,
Bert.