As far as I know, the Digi 003 rack only has one TOSLINK/ADAT input so you could only use one of the Behringer units for 8 more channels.
I've had 4 ADA8000s for about 9 years now. The mic pre amps are adequate if not brilliant and tend to get a bit noisy if you push the gain. i can generally plan things to keep higher output devices on the ADAs.
I believer Behringer has announced an ADA8200 to replace the 8000 and one of the claims is better (Midas) pre amps. I've not had a chance to try these.
For your remote control, Google "Control Surface". You should find a selection.
The pessimist sees the glass as half empty. The optimist sees it as half full. The realist just drains the darn thing and gets a refill!