Effective ways to upgrade a Music Hall MMF 2.2


I am researching ways to upgrade a Music Hall MMF 2.2 and would like to get some advice.

1. Change the platter to an acrylic one.
2. Add a Soundbox - this is intended to be for automating changing the speed from 33 to 45 with a click - why are folks indicating this would improve sound quality? Confused about that aspect.
3. Changing the cartridge - how high can I go for this type of turntable and arm? Will get a different counter weight if required.
4. Should I consider changing the arm? When do these things become ineffective? I.e., what role does the table itself play in the quality of the sound?
5. I would like to upgrade my phono stage from the NAD PP2 that I have. Would a Project Tube Box make a difference?

Thoughts welcome.
shugho
Schubert, I want to clarify something I said earlier. My listening does include some rock, though it's not hard or heavy. More like the James Taylor, Fleetwood Mac, Beatles, Paul Simon, Sting kind, with some Floyd, Dire Straits, Jethro Tull thrown in, as well as I am getting back into the Eurythmics, and some older classics (Animals, Mamas Papas). I hope the Nagaoka MP-150 is still a suitable choice for this type of music, along with the classical and jazz that dominates my listening.
Of course in lost you Schubert, I was thinking of the ML150, my bad.
Sorry :-)
Most cost effective and with immediate results #3...many choices here...I like shure 97me...warning though...if you have never changed a cart it can be challenging...simpler solution would be to upgrade stylus on current catridge if possible...at this price point Nad is a solid choice...I would personally upgrade to a new table before going with soundbox, platter, etc...good luck!
Most cost effective and with immediate results #3...many choices here...I like shure 97me...warning though...if you have never changed a cart it can be challenging...simpler solution would be to upgrade stylus on current catridge if possible...at this price point Nad is a solid choice...I would personally upgrade to a new table before going with soundbox, platter, etc...good luck!