I don't believe they are linked, at least not generally.
Including a house in NW is correct, according to the definition, but the house's value shouldn't be used in FIRECALC unless you plan to sell it and live off the proceeds. It should be considered an asset that could be sold if you run low on $ or no longer need to live there and need to spend the proceeds of a sale on long term care (tricky if there's a spouse who doesn't need LTC).
A few here disagree, but you should not include the NPV (net present value) of SS in FIRECALC; SS should be listed as additional income on the year you intend to take it [If you include the NPV of SS in FIRECALC and you have a bust before you start taking SS, you've lost the Sequence of Returns Risk gamble, run out of $, and can't yet take SS]. Including SS on the appropriate input shows the income arriving when it's planned, and it helps lower the future SORR once the SS income starts.
After reading thousands of SS posts here, I've come to the conclusion that there is no "best age to begin SS". It depends on too many factors (health, marital status, Survivor's benefit, Spousal benefits, etc.). For those in good health, with a partner who might benefit from Survivor's benefits, it's generally a good idea to wait at least until FRA, and age 70 if you can.