OK I'll chime in....
What Moore said is correct. You need to learn FHA guidelines on what type of carpet and quality of paint. Normally 16oz carpet 6pd pad. Neutral colors. Same with the paints...Sherwin Williams paints-off white flat.
As far as the discoloration. "Prime it silly" NOPE. You are looking at sticking your neck out for a heck of a liability lawsuit when the mold really grows. Not worth your risk. Get an IICRC Certified Contractor in your area that has an AMRT Certification and they can get this bid out.
www.iicrc.org PLEASE bid to "obtain a 3rd party professional estimate" and pay the guy/gal an estimate fee since 99% of the time you are
wasting your time. The banks normally have no intention of "fixing" the home but are using your estimate to "discount" the home your bid amount on the sale of home. The pro's need paid for their time.
Also, Don't take this wrong? The only contractors that normally get this type of work are "approved" vendors that KNOW what they are doing. Otherwise they send out a bid work order to a provider/contractor that has no clue who will waste everyones time (including yours) providing these estimates. The "knowledgable" P&P contractors know the "scam" and will call the banks bluff. Normally on a large bid we will get anywhere from $300 to $1000 depending on the number of skilled trades come in to provide estimates.