On the cartridge issue the Audio Technica AT440MLa could be the best $85 you could spend.

I doubt that a long ground wire would be of much concern (and just about any wire should be fine), however using long interconnects to get to the receiver may be. The concern is the additional capacitance contributed by the extension interconnect. MM (moving magnet) cartridges are sensitive to capacitance loading with too much causing a rolloff of high frequencies.

I suggest you go ahead (just lengthening the ground wire) and give a listen. If the sound is overly dull or lifeless you like have high frequency rolloff, if not then simply enjoy!