You mean 60 days or 45 days visa exempt? If either, he will have one 30 day extension available to him and potentially the unable to travel due to covid extension if they continue that beyond 27 September.
Can you sponsor him as a dependent? No.
Retirement, I'll let someone more knowledgeable than me on that answer that.
Chrome on laptop, wherever there's a drop down option use it and don't type manually in the box, where a date is needed use their calendar. Don't accept any autofill, where typing is needed do it manually, eg address.