loud noise fan: past pic I have seen was a dead mouse inside, that made the noise. You have to check it.
Heat: first of all switch microfilter, then test the temperature sensors for the IHKA.
On my website on the link to Johan and Sean the IHKA system is explained and shows where all the temp sensors sit.
Third question: might be a broken stepper motor or a broken flap. Also see Johan's website under heater, he changed the parts. But that is a lot of work, IHKA unit has to come out.
Or do a search for fix of broken stepper motor, I have posted that here several times with pics, how to fix a broken stepper motor again with some bracket.