Maybe this post should have gone under "Pro Audio Gear" I wasn't sure. :

Should the A/D and the D/A sound device(s) be seperated hardware or combined?

The converter will be one unit containing multiple I/O. Many, like the very good RME FF800 also incorporate high quality preamps.

Will I be bypassing the preamps on the sound card since I want to be sure I am only using the quality preamps in the chain?

The internal sound card of your Windows or Mac PC will be bypassed so don't worry about it's quality.

Is it necessary to have an analog or digital mixing board (desk) to assist me in this chain?

It's personal preference and there are many different feature sets. You can mix completely ITB (in the box - in the DAW software) or on the mixer or a combination of both. Something like the Presonus Studio Live is a fully functional digital mixer with the preamps and the A/D D/A converters built in. Plug it in and hook up your mics and instruments. The A&H Zed R16 is similar, but analog and not as feature-rich.

How important is the quality of the sound card? Does the purchase of outboard preamps make the internal sound card preamps irrelevant? If so am I then looking for a sound card without preamps?

Your PC sound card will be irrelevant. You want an interface with A/D D/A conversion. Then get the preamps you want if the interface doesn't have good ones or get an all-in-one mixer like mentioned. There's a hundred different options that will get you where you want to be.

Sorry for the barrage of questions

That's what this place is here for.

Budget?

Thanks for the info. What I meant by sound card is what you refer to as the RME FF800. So if I purchased outboard mic pres would I be bypassing the RME's pres? In terms of budget, I am gathering information to see the different paths I can take and get some costs. Here is my current setup:

Yamaha EMX5000/12 mixer --> Echo Layla --> DAW --> Monitors.

My problem right now is the Layla (very old) is failing on me and the mixers pres are average quality.

The RME pre is good. They are on 4 of the channels so a separate pre can be inserted onto one of the other inputs and bypass them.

How is the phantom power controlled? Is it for a group of inputs or can you turn it on for individual inputs?

thanks.

They're all different. I have a single channel preamp that has 48V and I have an 8-channel pre that you control the phantom power in pairs of channels so I can enable 48V on 1-2 and leave it off on 3-8. Just have to look at the specs on the unit you're interested in.

Well thanks for the information you have helped me a great deal. i just need to make some decisions now.