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
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!