ckaven,
1) I personally have no experience with SDIO interfaces to a processor - how fast is the interface you are using? I would just pay attention to the actual specs on the chip and create the shortest traces to connector as possible with minimal use of VIAs. A good rule of thumb is to route high speed digital traces or sensitive analog traces first. If you would like to setup bus routing to keep the traces together, you can set these up from the Ultiboard menu (Tools -> Group Editor). Use Ctrl+B to start the bus route and click on each starting pin you'd like to route within the group. Note that bus routing works best before routing other signals.
2) On the top/bottom ground pour, I would say 'it depends'. If you are planning to expose your design to a susceptible high externally 'noisy' environment (such as near an AC source or near boards with noisy communication signals or otherwise) than it may be a good idea. Basically a properly constructed ground plane can act as a 'Farrady' shield and limit the effects of noise on the inner layers (just make sure you are using solder mask on this pour). How many layers? - you may want to simply put a single ground plane (or planes) on the inner layers? You do need to be careful for a few reasons:
a) Remember any loops (especially a loop with a large contained area) can act as an antennae and so you can defeat the effectiveness of your grounding by causing an unintended loop - which can actually make the noise performance worse. If external EM signals cut through this 'loop' that will produce a 'noisy' ground plane.
b) If this is Rev A. (and you don't have the luxury of doing a second board), there exists the possibility that you may need to rework the board in some fashion. Sometimes the extra copper on top/bottom can be obtrusive to doing rework (especially if there is drilling for mounting holes or other things that may need to be done).
The best suggestion (if you have the luxury of doing a Rev B) is to go without the copper shield on top/bottom (maybe just a nice ground plane on an inner layer) and then determine if the noise performance/operation is adequate. If you do feel you have a noise issue you can experiment with external shields (steel sheet metal is best) and experiment if this helps to eliminate external noise. If it does help, it may then be appropriate to add the top/bottom shield (again warning 2a above)...
Regards,
Pat Noonan
