This seems to be one of those areas where the private companies who are designing the competing landers aren’t saying too much.
From discussions I’ve read about this on line it looks like for Space-X design the main engines will shutdown at, say, 100 metres and the final part of the descent will be flown on a ring of relatively low powered thrusters mounted roughly half way up the vehicle to avoid the impingement you mention.
as for the CofG issue….not read much by way of opinions on that