I got the 55% residual and the 0.002751 money factor by crunching the numbers in the Solterra lease "promotion" I posted above. For 36 months/10,000 miles per year.
The 53% residual and 0.00244 money factor were given to me by someone I know who works in automotive incentives (who has access to the figures for all brands). Also 36 months, 10,000 miles per year.
Apparently, the thing that's "set in stone" is the residual, but the MF can vary depending on your credit, and how much money the dealership wants to make on the lease (so it's useful to be able to calculate the MF since in most states the dealerships aren't required to tell you what they're using).
I had also heard (and my source confirmed) that one should put as little down toward a lease as possible. It sounds like that would be just the $7,500 if that gets passed through.
The total finance charge you pay on the lease is the product of the money factor times the sum of (the residual + ACC, the adjusted capitalized cost) times the number of months in the lease.
You cannot affect the residual, but you can affect the ACC. It is the sum of (Agreed Selling Price plus Aquisition Fee (fixed) plus state registration/titling fees plus Dealer Document Processing Fee plus Sales Tax minus any credits you have, including e.g. the Federal EV credit, as well as trade-in or cash up-front (neither of last two a good idea)).
In addition to the financing cost ("rent charge"), your monthly lease payment includes each month's share of the depreciation (total depreciation divided by months).
Depreciation is the difference between the ACC and the residual. The lower the ACC, the lower the depreciation charge, so lowering the ACC lowers two components of your monthly payment.
But, whatever money you pay up-front is lost forever if you have to terminate the lease because the vehicle got totaled. Same with making extra monthly payments. Unlike with a loan, you have no equity in the lease so there's nothing to be gained by making a payment early. It doesn't reduce future finance charges, as it would with a loan.
Once you have a lease, you can each month find out how much it would cost to buy out the lease. At that point, you obviously avoid paying any future finance charges. For example on my current 2021 Outback lease, if I buy it out today (assuming I'm going to at lease-end anyway), I save about $600 compared to the residual plus my remaining 12 payments. I would weigh that $600 against the opportunity cost of the money I have to come up with to pay off the lease. I also save the lease disposition charge ($300), but I do have to pay all the sales tax due (including local) on the buyout cost, along with the registration/titling fees all over again (so the title can be issued in my name, without the leasing company name on there).
I'm sure there are good sources for all this info, I've just gradually absorbed most of it over the course of 4 years and 2 leases.