I am having trouble with Send in Bitcoin Core.   (I have a separate thread for that but that thread is getting a bit technical now).

Much want some help with just the very core basics.

When it comes to:

Is that default ok for most "Send" transactions? Or does it have to be adjusted for most people, most transactions, for everyone?

Transaction Fees.
There is a default recommended 0.00004978 BTC/kvb Estimated to begin confirmations within 6 blocks.

What does this really mean?
Should one go for 4 or 2 blocks?

(I am willing to pay to get this done now, do not care about USD 20-50-100 transactions fees. Just want it done.)

Or is it better to go with Custom per kilobyte. Is there a risk with that?

Any advice appreciated.