Design of anti-alias filter for ADC, with oversampling and averaging

Hi,
I am trying to design proper anti-aliasing filters for a new hobby
project (digital control of a quad-rotor flying robot - see previous
post for more questions). Here are the specifics:
* My sensors are analog MEMS accelerometers and gyroscopes. I'll have
at least 6 sensors to process, at least initially.
* I will be using a microcontroller with 10-12 bit built-in ADCs to
process the sensor data (and implement the control loops)
* I'd like to keep part counts and costs to a minimum (of course)
* I'd like to employ oversampling so I can make use of an analog anti-
alias filter with a (relatively) low number of poles
* I'll need to implement a digital filter + decimation to get down to
the desired sample rate
* I'd like to average the samples (prior to the digital filter?
although the averager is itself a digital filter) to improve the
effective number of bits of resolution.
So, here are my questions:
* Can anyone recommend a good references for such a design, combining
these elements?
* How important is it to use a Bessel filter (linear phase) vs
butterworth (flat passband response) in the analog filter stage?
* What kinds of filter-on-a-chip IC packages exist out there? I think
I'd prefer a switched capacitor or other easily varied type of
configuration (so I can make certain filter changes without altering
hardware)
* Are there any microcontrollers that automate the sampling and
digital filtering processing, with minimal direct intervention? It
looks as if the Luminary Micro ARM line has some hardware sample
averaging capability, for example, but it is not clear if it can
handle 6 simultaneous analog channels.
Thanks in advance
Roy