Upgrade Classic to Premium-Gold, Settings-Backup? Payment ways?

Hello, I've been using Locus Classic since 2019 and now want to upgrade to Premium Gold.

1. Will all settings from "Classic" be transferred during the upgrade? Will all routes, tracks, and points be transferred?

2. Should I make a backup in "Classic" before upgrading? If so, how do I do that? Backups to Dropbox haven't worked for months, and Google Drive doesn't seem to work either!

3. Payment methods: I see on your website that I can purchase a one-year Premium license even without the Google Play Store. Is that correct? I would go to "Go Premium" in the app after installing LocusMap 4... (but I don't need a voucher, just a one-year license for my tablet and smartphone).
What payment methods can I choose? PayPal? Visa card?

Thanks in advance!