In most cases a home inspection isn't going to catch those things, they only look for the obvious and outwardly dangerous. READ your report you will find in small print a disclaimer that protects them from any kind of lawsuit.
The best home inspector is YOU. IMHO there's not a darn thing you can do but suck it up.

Did you view the house before you bought it. Many of the items mentioned would be obvious on a walk thru.
The inspector is not a code inspector.
As far as recourse, read your contract and disclosure the inspector gave you.
For example the inspector probably states not responsible for concealed damage as you state in your first item.
Did you not physically view your cooktop and micro?

Well, we did view the house, albeit with four kids running around. There were many dangers, spacing of the balusters and an unfenced pool that made it difficult to actually inspect the house ourselves while trying to watch the kids. My husband came in from out of town to quickly go over the inspection with the inspector. In the rush, I guess many things were missed. We trusted the inspector to let us know what items would be of concern to us. Guess that was stupid. Why even hire one???

Rule 535.228 lists all the things that should have been on that inspection, but never came up.

http://info.sos.state.tx.us/pls/pub/readtac$ext.TacPage?sl=R&app=9&p_dir=&p_rloc=&p_tloc=&p_ploc=&pg=1&p_tac=&ti=22&pt=23&ch=535&rl=228

"Well, we did view the house, albeit with four kids running around."

Why did you bring the kids? How important was this inspection to you considering the distraction?

We didn't have any choice but to bring the kids, we don't know a soul here, and are hours away from anyone we do know. The inspection was important enough for us to take turns watching the kids at the inspection so we could go over everything that the inspector noted. No, we did not check grade at the foundation ourselves, or look at and open every one of the 45 windows. We did not measure the stairs or check for a dishwasher leak. We paid him to do that. He showed us the deficiencies he had found, we discussed them, and that was that. We move in, begin making some repairs that we knew about, and then discover all this.

An excellent inspector is only going to view/inspect about 60% of any given house. They are not going to view anything behind paneling, behind a cupboard or pull out a dishwasher and look behind it. They are not code inspectors. If you feel you have a case, hire an attorney and get your inspection fee back ... that is usually all you are entitled to.

 Rotten windows that produced mold underneath the windows, but concealed by paneling

Inspectors cannot see concealed damage. They best they might have noted was the rotted windows, but cheap windows are cheap windows (depending on what you mean by "rotten.")

 Sloped floor (on the 2nd floor) about 5-6" over about 10 feet

Probably should have been noted, but seems like an obvious issue that may have no structural implications.

 9" high stair risers
 21" handrail (he did mention the 4" spacing between the posts, which we knew we would need to repair)

What was the local code when the place was built?
Anything built to the code in effect at teh time is normally grandfathered.

 negative drainage toward house on both sides, including the pool deck sloping toward the house

Sounds readily obvious.

 leak in plumbing outside of house (pooled water in flower bed). Neighbors told us they had seen people working out there for days before we bought.

What was on the seller's disclosure?
They may have though the item was repaired.

 fireplace gas leak

Unless it was so huge you could easily smell it, the inspector is not a code official.
They are not going to soap every gas pipe connection.

 36" gas cooktop that is only 18" below the 30" microhood and cabinets

This is likely perfectly acceptable.
18 inches is a typical minimum clearance.

 water damage around the dishwasher, rotting the cabinets

If it was not visually observable the inspector is likely off the hook.

In many cases (absent a spefic state law) the inspector is only liable for the cost of the inspection unless there was gross negligence (and even then it can be tough to win enough to be worth the effort).

If you read the contract with the inspector you will probably find he is liable only up to the cost of the inspection. The reason for this is that they are not an insurance policy. If you want them to be fully liable for anything they could miss the inspection would cost many thousands of dollars, and no one would accept that.

I've never heard of an inspector being required to point where the house is out of code compliance. In an older house it could take an inspector days to document that. My house is only 3 years old and it already doesn't meet current code.

How is this approaching $100K? You are not required to bring the house up to code. Are you rebuilding the staircase? Unless it is a tripping hazard (which is usually caused by tread heights varying, not being too tall), why not just leave it as is? Worry about the things that will get worse (the water damage).