[wiswind]

I would look at the front and rear heat issues as separate problems.
Front, it is possible but not at all likely to be a issue with a clogged heater core.
This is because the coolant ALWAYS flows through the heater core, regardless of your temperature setting.
This prevents stuff from settling out in there during the warm times of the year.

Blend door issue is very common.
Maybe the linkage between the electric motor that drives it, and the door is broken.....letting the door move about at will with each bump you hit.

Rear heat......check to see if the heater line is HOT back there.
If it is, then you have a blend door issue back there as well.