It depends on what you need. If you want something to receive wifi for your windows 10, they should all work. And I would recommend the TL-WN821N V5 since it is the only wireless adapter you listed....

have you tried reboot? or back up the settings first then reset it and later restore the settings.

it is enabled by default in the software.

how many plugs do you have? what do you mean alexa can not find second iphone? one cloud account can be login using different phones.

you can plug them next to the router during the setup process, then after the setup, move them to where you want.

i think there is kind of software can do that, you can google that and find suitable on.