I was going to point you to Beagle's site but he did it already.
A good interface can work with any DAW... I would not use the DAW software that comes packaged with the interface since it is normally one of the LE versions.... like a demo version with limited abilities.
The USB interfaces are very good now. Since you are using Music Creator 3 (did I see that correctly?) I would say you don't need any more then a 2 audio channel interface because MC only supports 2 inputs at a time.
I'd recommend an upgrade to MC6 now, or to X1e. The price is reasonable, AND..... it has some real performance improvements over MC3...and it also has some nice sampled sounds in it. Cakewalk Sound Center alone is worth the price IMHO.
I just upgraded (they call it a crossgrade) to X1essentials and it is sweet. Worth the cost for sure. That allows more inputs then the limit of 2 with MC. Look at Beagle's site and see what interface will give you what you need.
Be aware that firewire doesn't always work with chipsets other then the TI chipset. Also USB 2 & 3 are now faster then the Firewire ports.... when I bought my firewire Saffire, that was not the case.
My suggestion, visit a music store and have a look at the interfaces they sell. Take with the staff and see what they recommend... but be educated BEFORE you walk in, so you don't buy something that is not what you really need.
Edit: one more thing.... all my mixing is done in the box. I have no need for an external mixing desk. All my stuff goes straight to the interface..... if you get one that has good preamps, you will not need any external mixer...unless you really just want to use one from old habit.