Always/Auto just control when you want it to apply so it's purely a personal decision. 70% is our recommended starting point but there is no one percentage that works best for every connection. You'll need to do some fine tuning/trial & error to find what works best for you.
You are on an old version so the cloud will work better with the latest version.
Ping Assist won't be present on that version
I'm not aware of a visual bug on the ping panel so this is likely reporting the connection as it is
Yes I'd suggest factory resetting after upgrading, especially as you're doing a big jump in versions.
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