I would first sit down and run your situation through FIREcalc to check to see if your spending is sustainable. Ignoring the home equity (unless you plan to downsize significantly), $110K / $1825K is a bit on the precarious side except that you have SS coming in at some point. FIREcalc can crunch the numbers for you - you can put in your assets and income streams and spending and it will run a historical analysis of how your situation would have turned out.
I would run opensocialsecurity.com with your SS situation. It may recommend the higher earner taking SS later and the other earner taking at 62, but see what it says. Look at the sensitivity analysis at the bottom to see how much it matters (it probably won't matter much when you claim).
Personally I plan to delay SS to do as much Roth conversions as makes sense for me.
I personally spend from my taxable as needed and then do Roth conversions up to a tax rate that I am willing to pay knowing my tax rate will be higher later. I use the Case Study Spreadsheet (available on a thread here on MMM) to analyze this each year. It requires genuine Excel to run the macros that generate the marginal tax rate analysis graph - I go to the library for this.
Another Roth conversion impact is that, as part of AGI, it affects anything derived from AGI, which notably includes ACA subsidies. So the more Roth conversions you do, the lower your ACA subsidies. Other AGI things are state taxes and FAFSA SAI calculations.
On the inheritance, if you're going to plan around it, you probably should find out if it's going to come as life insurance payout, traditional IRA, Roth IRA, real estate, or whatever. The taxation to you of each of these differs, and if you're going to plan you might as well try to plan well. But I will repeat the standard advice, that that inheritance money could disappear in any number of ways: they could marry the pool girl/guy and change their will, they could lose it to a scam, or they could lose it to an expensive end of life illness. Only you can decide how you want to handle those things, but "don't count on it yet" is the most conservative.
IRMAA applies at age 65 and there is a 2 year lookback, so your tax return when you turn 63 is where it starts to matter. It is basically an extra 2-7% income tax. Put it in your model, but it likely won't change any of the big building blocks of your plan (it could change things on the edges).
Whether there is an inheritance tax bomb depends on the nature of the inheritance. The inheritance itself generally isn't taxable - you probably know that - but any income that the inheritance throws off is taxable to you generally, and traditional IRAs generally are required to be drained within 10 years of death of the owner and RMDs are also generally required during that 10 year period.
I agree you should take a hard look at Roth conversions. Also disclaimers and QCDs if you have plenty of excess.