Even though you're not expect the analog side to be too high speed, your a/d nevertheless may be running at 100msps - so it will do a good job of digitising noise - at very high speed! You'll need to count you nano seconds carefully when doing the digital design - a new sample every 10nS doesn't leave much fat - add a buffer, a few nanoseconds here, ringing on the data lines, a few more nano seconds there and that's not taking into account setup and hold times. Keep the data lines from the adc as short as possible, as the more capacitance on the data lines the more ground bounce you may suffer from which will invariably get into your analog side.

Like Erik, we're not trying to discourage you, but there's treacherous waters ahead! Besides, the best lesson is a hard-won lesson even though it hurts!!!