Justin, the 404 will more definitely accommodate both climbing and rando boots. And I would heartily recommend the laser over either the MLT4 or TLT4; it'll ski much better than either. The MLT4 isn't even a ski boot. Stick with the Lasers (IMHO).
Mntgirl, I suspect that you'll ski in the mountain boots once, and never again. If/when you have the cash, get some Dynafits and stick with the Lasers. Rando boots climb everything but rock/mixed quite well. Unless you're skiing a flat approach to some heinous ice/mixed/burlfest, there's no good reason not to use the rando boots.
Oh, yeah, the MX7 is a decent ski. Not truly high-end, but certainly a decent all-around backcountry ski, don't thrash them without a second thought. And they'll easily take a second mount, so putting a different binding on them in the future will work just fine.
Have fun, skiing is a blast.