I agree with Howard......check their financial situation first. I found out the hard way that it's better to make the investment from the start rather than try to go cheap and play catch-up.
I would go with the bigger tank - 120g. It won't take up much more room than the 90g and they will appreciate the extra space as their tank fills up.
If they have any skills whatsoever I would advise them to build the stand and canopy.......there are a lot more customizations they can make to suit their individual needs. If not, have them look around a lot before they commit.
Go with MH.......I've experienced and read too many posts about people trying to go cheap on lights and having their tank go to H-E-double hocky sticks
Definately go with the sump.......incorporate a fuge in there if possible. Go with the Mag if they're going submersible and definately a SCWD or Oceans Motions (depending on budget).
IMHO - and based on my experience, look on the boards at RC, SWF and the local clubs and buy the stuff used. You can get a lot more for your money that way.