Help with delat sigma modulators

Hello,

I'm looking at purchasing the following from ADI for a motor development effort,

https://wiki.analog.com/resources/eval/user-guides/ad-fmcmotcon2-ebz/introduction

I noticed that the current ADCs for measuring current through the motor windings are actually delta sigma modulators and not ADCs.  I am planning on using a zedboard (zynq SoC) so this isn't a huge deal, but these are new to me as an FPGA guy and require some DSP.  I was wondering if someone could help me with a few concept questions regarding these modulators.

1. Why are these used instead of full delta sigma ADCs or SAR adcs?

2. It looks like these are demodulated and decimated by a CIC filter.  This doesn't seem too hard, but are there any other logic CIC blocks required besides the CIC filters?  

3. Does ADI have an app note on how to develop the DSP side logic for these parts besides the example in the datasheet?

4. Is a 3'd order CIC filter enough or should I be using a 4'th or 5'th for good measure.  I've read that going above that is not a good idea and not worth the effort.

5. To get this part up and running is it really as simple as using the HDL provided in the datasheet?

Any guidance is greatly appreciated.