The 4% rule is not the calculation where "all other things factored in, you need THIS much."
The 4% rule is the calculation where your portfolio is basically unlikely to shrink. Ergo, all other considerations, like Social Security or inheritances etc, are extra padding to your income beyond what you generate from your 4% situation, and are not at all accounted for by the 4% rule. Very aggressive and optimistic investors could lower the 4% rule by such considerations if that was their thing, but we don't generally recommend it. You take the 4% rule and apply it to your own annual spending and spending projections. 4% is just the Trinity Study's verdict on a safe withdrawal number, not an explanation in any way evaluating what YOU need annually, which you have to determine, plug into the 4% rule, and get your target savings goal.
See above post for your 401k conversion options.
Yes, you need to pay for living before you access your 401k, silly. You can do that with Roth withdrawals, you can do that with liquid savings (but that's an awfully investment-growth-poor choice), you can do that by withdrawing from a separate, pre-normal-retirement-age taxable brokerage account. Many people have a post-59.5 bundle of investments and a pre-59.5 bundle, especially if they're not big in real estate properties.