Mixer Confusion?, Digital or Analog? Options

[iShawn]

I understand pretty well what an analog mixer does...you end up mixing everything for a live event to the mains for your show. I know they use mixers in recording...and with all of the tracks some have and the EQ'ing and plugin control I see why. But it seems that digital mixers fall into two categories.

Category 1
In-line digital mixer. These I don't seem to understand too well. Everything is plugged in using conventional inputs as normal and then somehow they maintain (I guess) the automation of the channel levels and other knobs through the computer magically. These I have most confusion over, for they maintain automation however they don't have any connection to the computer's software.

Category 2
Post-mixers. These connect through a MIDI port or USB port or some sort of way directly into the computer, and although they don't have any acutal line-level analog inputs in them, they take all the tracks of the software and provide pretty much a hands-on approach to mixing and finalizing a large-sized project that otherwise would be tedious to do with just a mouse.

I found a really cool one of Category 2: the TASCAM US-2400 that provides a USB connection to the computer for 24 tracks of automation with other real-time controls. As far as I know, this can be used in Cubase, Logic, PT, etc where you can control what the software is doing out of the computer with just a USB port. Is this correct? although all I need now is just a firepod and cubase LE, eventually I wanted to build upon that, and with the linking of multiple Firepods, I figure I could use those as my interface(s) and use the US2400 as a way to mix everything where I would use a lot of different tracks/controls/plugins to control.

So...after reviewing this, please let me know if I am right, or what I might be confused about. For this digital realm can be overwhelming at times...
|Keep Swinging|

[iShawn]

For example:
If I wanted to plug a MOTU 24I/O into a computer, and it jas just the line-level inputs on the back of it, what would you suggest for an in-line setup where you can automate the faders and other controls? Or can you?