"issues" could be anything.
MSI A520M-A Pro to Gigabyte B550M Aorus Elite.
Yes, a fresh install is strongly recommended.
... As for number 3, what are the issues i would be "chasing" for weeks/months? ...
A few example of 'issues'...
SLEEP never works. Or when it does it doesn't come out of sleep.
Installing updates for software can be "iffy". Especially things like GPU drivers, which are always updating.
Some applications don't find their support files even though they're in the exact same folder location they always were before.
Some applications simply refuse to work and can't be installed again because the installer thinks it's already installed; or uninstalled because the uninstaller refuses to do it completely.
Those are some of the problems I chased when I did an SSD swap into a new motherboard/CPU. At first all went great and I could chase down most of the issues (except the sleep/hibernate problem). I found that a Repair Install with In Place Upgrade fixed most problems (except sleep/hibernate issues) but I was never comfortable with it so I just broke down and clean installed.
It's not that hard to 'clean install', just get organized. Keep all your games and 'big data' on a separate data drive is the first thing, and all you documents in the My Documents folder, copy that to a spare drive. Now clean install. Yes you have to reinstall all your apps and customize your desktop but it's not that hard. Or you can get an app like Macrium to do it all for you.