Yes, like posted in the link above 2666Mhz is the max supported speed for that CPU, anything above that is overclocking and likely to cause issues with Ryzen and Linux.
A little better, at least the first one, but can't help with this, outside my wheel house, moved the thread to the VM sub-forum which the more indicated one and hopefully someone else can help.
Yes, no output is normal, but attention to this:
After the command is entered the GUI can't be refreshed or else it won't take, and the array will begin syncing parity instead of rebuilding the disk.
Yes, that's it, 29 is for parity2 when it's not installed which is also your case, so it's also invalid, but type the command, don't copy/paste from the forum.
Only if that it making it use a zone with marginal sectors.
It's usually good to give a disk a second chance when it's a one time thing but if it keeps having read errors better to replace it.
You can use pv but current dd already shows progress with the status=progress option, as for byte size anything above 1M should be good for performance.
Link isn't working but assuming it's a multiple disk enclosure running from a single eSata port it's not recommended, both for performance and reliability, since it will use a Sata port multiplier, if you really need external look for a SAS enclosure.