Good Afternoon,

My name is Jimmy Criswell and I live in Midlothian Texas (Climate Zone 3 – about 15 miles south of Dallas).  I live in a 1984 ranch style 1450 square foot home with a hip roof with a low pitch.  It actually has 2 hips because the garage is on the side of the house where you can faintly see the truck.  I only have about 4″ between the exterior top plate and the roof sheathing.
House has kraft faced R11 fiberglass batts on all exterior walls and R-44 fiberglass in the ceiling.  We have recently had a bad case of rodent activity which I have corrected.  I now have to go through and get all 20″ of insulation removed due to the mice droppings and urine.   My house currently has only 8′ ceilings.  I have some money set aside but am a single income family and may have to do this in stages so helping me with priorities would be appreciated as well.

I am looking for advice on how to approach my problems.

1. I am debating on a proper strategy as I have air sealed some of the attic but nothing else in the house.  How should I approach the removal and reinstall of insulation since it will be done diy and I have to de-sanitize as I go. The room with 2 exterior walls is about 5 degrees colder than the other rooms in the house this time of year.  I am willing to remove drywall to increase R value of exterior walls as well as airseal.  Recommendations?  I have thought about polyiso and batts.

2. We will be installing new central air heat pump at the beginning of March.  I am looking for ways to get the ducts inside as air handler is in closet but supply plenum and ducts are in attic but  am on hold from removing insulation to re-insulate due to current weather (cold) and the lack of a strategy.  Our home will get toasty hot while the electric heat runs for just a short few minutes but then gets cold again rather quickly resulting in short cycling.  I am not sure it runs all day even in the few 110 degree days we get throughout the summer and probably only then does it properly de-humidfy.  Currently a 3 ton 13 seer unmatched unit with 2007 outdoor unit and original air handler which I am pretty sure is oversized.

3.I am going to have a difficult time creating an airtight air barrier due to the lack of workable height in the attic where the eaves are met.  What is the best strategy to deal with this?  What type of insulation and where should it be placed?  Currently have soffit vents (not enought) and 2 ridge vents.  One for the house and another partitioned hip over the attached garage.

I would like to know what order to pursue these problems in as indoor air quality and comfort are my 2 largest concerns.  We are either hot or freezing all the time.  Any help would be appreciated.  Windows were replaced in 2016 with dual pane argon filled low e 366 glass.

I am very handy and can complete much of this on my own.  My uncle is in hvac and can help me upgrade the hvac system and ducts though I am considering raised soffits above the attic floor to semi condition the ductwork.  I am working on a budget of about 12,000 and believe I can do a 16 seer carrier for about $4-5,000.