Regarding the recommended 36.56%, does size matter? In other words, does the size of a transaction change the recommended mining cost as a percentage? For example, at that day/time and those Electrum defaults, if the transfer was for 1 BTC, would it likely be a $20,000 fee recommended for reasonable processing speed?
No. Transaction fee depends on transaction size, which is measured in virtual bytes (vbytes)
The size of the transaction is calculated based on the address format (legacy occupy more vbytes than segwit) and the number of inputs and outputs.
The outputs are the number of destination addresses, and they are often 2 (one destination and one change address, back to your wallet).
THe inputs is a little more complicated, but they are basically the number of times you received bitcoin. If you received a lot of times, you will pay more in taxes than if you received only once, even if it is in the same address.
I made this tool where you can play around with transaction size X number of input/outputs and address format
https://bitcoindata.science/plot-your-transaction-in-mempool.html For example, at that day/time and those Electrum defaults, if the transfer was for 1 BTC, would it likely be a $20,000 fee recommended for reasonable processing speed?
(Aside: I’m having trouble reconciling a 5-digit fee cost of transferring a single bitcoin with a recent Coindesk story reporting “
Per multiple sources, the average fee is roughly $59.”)
https://www.coindesk.com/bitcoin-transaction-fees-more-expensive-than-everYou can go to
https://mempool.space and see what is the recommened fee per vbyte there.
What is important when you are trying to set the fee is the "sat/vbyte" option. This is basically the only thing you will have control when making a transaction, and this is how much you are paying per byte in your transaction.
The more you pay per byte, the faster it will be confirmed. As you cannot change the transaction size anymore (you already choose your address format and how many inputs you have) you will ahve to pay for its "space" in the blockchain.
Which wallet you are using? You should use no more than 50 sat/byte now, which won't cost you a lot.