Hi Jollis,
I'll try and answer your query as best I understand it, but I'm pretty sure that my more experienced friends on the forum will also add or even subtract to these comments and hopefully help you with your decision
Firstly the D8B has more than enough Line inputs to accommodate your keyboards outs and/or any other midi gear that you may want to run. Just plug them directly into the Line inputs in the rear of the D8B, adjust your trims as you would conventionally and play away. (A good patchbay configured correctly will really help with routing). The first 12 inputs on the Mic/Line Layer of the board are both Mic/Line switchable and can cater for your mic inputs. Mackie PREs are pretty good, but you may wish to use third party preamps.
Addressing your question as to what I/O cards to use is pretty much dependent on how you actually want to use the console. The there are options available to you as far as digital and analogue ins and outs are concerned, so you may want to cater for both. This link should give you an idea and help you in choosing which cards to go for : http:\\www.sonido-7.com/d8b/inout.html
As for sync cards, the D8B comes standard with a stock word clock card and for all intents and purposes works ok but, and there's always a but, for accurate and absolute sample rate and sync you would do much better in opting for the optional Apogee Word Clock Card. (my experience with the clocking issue has taught me that the stock card just doesn't handle as good as the Apogee and cannot be configure to switch between Internal and Wordclock either. It's just set to run either at 44.1 or 48 sample rate). That said Q2 can now be answered. I've got a dual D8B system running with the Apogee Word Clocks and although I've managed to slave them both at one time or another, I can say that the D8B in general prefers to be the master. I remember reading that that in manual, but maybe one of my D8B peers may be able to shed some more light on the subject based on their own experience.
As for bringing in the ADAT, that's I believe just a question of how you intend to use it. The I/O digital/analogue scenario is pretty much the same. Just select the correct I/O card (I would probably opt for the OPT 8 I/O) and slave it to the D8B. If you intend to use more than two word clock devices it may be a good idea to connect them to a master word clock generator. The D8B will work happily slaved to a good Master Clock, that is if you're incorporating the Apogee Word Clock option as explained above.
Question 3 is a matter of preference. You could use the submix option as you've described. The routing cababilities of the D8B is phenomenal. If I'm not wrong the Delta 1010 has 10 in and 10 outs including the S/PDIF option and also has Word Clock too. But you would be limited to a total of five stereo pairs for mixdown in logic. You could out them to the D8B as stems and mixdown through the board in a variety of ways, but I would prefer to have more outs from the DAW. That would mean looking for a more flexible interface for your intended rig.
Q5 is again optional, but again in my opinion, if you're going to utilize the D8B fully, then invest in at least one UFX card. I have four and I'm looking for another two. You may find a D8B with an MFX card pre-installed. I remember reading somewhere that it comes standard with one. The MFX cards runs Reverb FX as such and if you have two installed, a plugin called Vocal Studio is fully enabled for use. The FAT channel is accessible for EQ, Comp, Gate etc processing, but you will need to have one or more UFX cards installed to acces the other range of plugins available and these will need to be authorized before use. They are available on the main Mackie site: http:\\www.mackie.com/products/d8b_v5/plugin_info.html
V 5.1 along with SP3 is a must if you want to utilize the full plugins array available for the D8B. SP3 is free and downloadable from the main Mackie site. You will have to authorize v5.1 if it is not already authorized or you will only have access to that platform for only seven minutes after boot. V3 should work without authorization.
HUI will work fine under v5.1 in logic. I've tested it in Logic 9x and use it every day in Pro Tools 10. It's reliant on good midi connection and once configured correctly works well on most DAWs. I hope this a least helps you somewhat in making your decision.
Andy
Knowledge is the beginning of Wisdom... Let the learning begin.