There are some skills that I suggest every homeowner learns in order to avoid high repair bills (in order I usually do them):-Fix minor roof leaks & repair siding/exterior-Fix water supply leaks with compression fittings or hose clamps if needed-Install lights, replace bad receptacles, switches, or breakers-Install electric water heater if needed-Fix subfloor & sturdy up framing if needed-Fix/replace windows/doors/glass and install locks-Drywall/mud, brush&roll paint-Install floor (floating/tile) and cut/install trim-Install toilets/sinks/cabinets/faucets-install mini split units if no functioning ductwork

In July I completed a lot of updates to the house (new well, new 200 amp electrical service and panel, new windows, replaced forced air ductwork, added a bathroom. 

there is nothing wrong with it, most microwaves have that option and do not have to be vented out, even though as a contractor i prefer them to vent out. if the existing pipe already vents out, which it probably does if there is a pipe in the cabinet already. what you would have to do is unscrew the 2 or 3 screws in the top cabinet that screw down into the microwave ( if not there then there may be 2 bolts in the front of the unit behind the cover that have to be loosened) that will loosen the microwave, then its a matter of taking the screws out that hold the fan at the top back, pull the blower fan out and change the direction so that it faces up, screw the fan back to the unit and put the microwave back up and bolting it. check to make sure the fan connects to the duct work, if not, add a piece of sheet metal to connect and seal that joint. btw you may want to unplug the microwave before doing so, just for safety reasons.

I just had the duct work and furnace cleaned today.  

On the side, for the past 12+ years, I've been a hammer-swinger for the two residences I own, doing literally everything except roofing (yep, everything, including plumbing, electrical, ductwork, flooring, demolition, framing, drywall, brick-laying, windows, cabinets...... etc).

As in, duct work? 

.#1 - if what you wrote was true, you may be able to utilize much of the existing duct work. 

The rest of the renovations are all manageable for us-  New kitchen, new heating system ( ductwork all done), flooring and paint, among other items.

I don't always take her suggestions but it gives me a good idea on what to do.Kitchen Gut (medium grade SS appliances & Granite) - about $40/sq ftHVAC - Duct work - $2.50/sq ftHVAC - Compressor - $1,750 + ($1.00/sq ft)HVAC - Heating Unit - $2,000Those are quick estimate numbers that I have found to be good for North Texas.

The rest of the renovations are all manageable for us- New kitchen, new heating system ( ductwork all done), flooring and paint, among other items.