"Under the knee walls I was planning on adding a batt and blocking with styrofoam and sealing the perimeter with spray foam. Is this acceptable?" --- so long as the attics are connected by air channels, you need to cover the foamboard to meet minimum fire-code, 220.127.116.11: http://building.dow.com/ee/pdf/ESR-2142.pdf
"When you say install Tyvek on the Attic side, Do you mean fasten the house wrap to the backside of the knee wall framing with the logo facing outward. (as would be applied to the exterior sheathing)."----- Yes.
"Is this designed to limit airflow into the interior?" ----- Exactly, keep the moving attic air out of the fiberglass: The "biggest loser" in fiberglass insulation....
"Hold insulation in place?" --- would also help, though I would use foamboard with a covering as stated earlier. I would air-seal the drywall on the room side: http://www.buildingscience.com/docum...wall-approach/
"In other words, just installing a section of house wrap in between the two sections of faced insulation. Would this again be installed with the logo face up...this time towards the interior?' ----- yes, cover any f.g. batt edges from air. Not on the rake ceiling, only on the side walls. http://www.buildingscience.com/docum...archterm=insul
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!