OK, let's drop back to fundamentals:
25x is rule of thumb for what you need in investments to think about retirement, early or otherwise. But some things that could require less:
- you will pay off the mortgage, so you only need 25x your core expenses plus whatever it takes to pay off the mortgage, or:
(25 * (25k-8k)) + 8k*7 years = $425k + 56k = 481k+/-
https://www.gocurrycracker.com/what-is-your-retirement-number-the-4-rule/You can subtract from this due to Social Security - If SS income is 16k per year, you only need enough $ to get you to SS age, not enough to fund a 30+ year retirement. So only about 15 years' worth. Or let's say SS is 8k per year, then you need enough to reliably fund the other half of your core cost of living.
https://www.gocurrycracker.com/social-security-and-early-retirement/re: 20% tax withholding - withholding is not the same as tax paid. You'll get most/all of this back at tax time. It does affect cash flow.
Your questions:
1) yes, you could use the 72t to provide only a portion of your total annual spending. The rest would come from whichever source was best.
2) That's now how a 72t works. The amount you withdraw annually is based on your life expectancy. Using current interest rates, you need $250k to get $10k/year.
3) Should you contribute more to 403b/457 today? You decide this based on comparing your current tax rate to your rate in retirement.
If your current federal tax rate is 22%, and you can pay lower later, then it is best to contribute now for tax savings at 22%. If your current tax rate is 12%, and you expect to pay at a higher rate in retirement (say 25-37%) then it is best to NOT contribute to 457 and do Roth or taxable account.
In Retirement, you could choose to do just withdraw from your 403b and pay the 10% penalty. Maybe 10% is a lower tax + penalty than you pay now, in which case this is a fine way to go.
You'll also might pay some income tax on that withdrawal. It could be 0%. But it might be 10% or 12%. So now your effective tax + penalty rate is 20-22%.
Those withdrawals will also reduce ACA subsidies at a rate of 15%. $1 in income loses 15 cents in subsidy. This could push the effective tax rate up as high as 37%.
https://www.gocurrycracker.com/obamacare-optimization-early-retirement/In short, compare current marginal rate to retirement marginal rate.
new 1) this is the same as question 3 above - if you pay a higher tax rate now than in retirement, contribute to retirement accounts. If you don't, then don't. Then you do a 72t or Roth conversion ladder to access those funds. It wouldn't make sense to choose to pay more tax now just to have some dollars outside the retirement account.
new 2) this isn't how capital gain harvesting works. If all you are doing is harvesting gains you have the same number of shares before and after harvesting. You sell at the current market price and buy at the current market price.
https://www.gocurrycracker.com/long-term-long-term-capital-gains/Higher basis means lower potential future taxes (say 10 years from now.)
An example:
https://www.gocurrycracker.com/harvesting-massive-capital-gains/In the original comment you suggested putting 50k into retirement accounts, so I assumed your income was $100k+. If income is $50k as you outline here, then your highest Federal tax rate on income is going to be 12%.
When you consider that the ACA tax is 15% up to 300% FPL, then tax now (12%) is less than tax in retirement (15%+.) In that case, NOT contributing to retirement accounts beyond the amount that gets a 401k match is the winner mathematically.