Actually, Free version is enough. Paid version does have the so-called "ransomware protection" and Web protection. However, I personally don't think Avira's ransomware protection technology works, and Avira heavily relies on APC to detect and block new threats (including ransomware), according to my testing. APC is available in the Free version. If APC fails to detect malware, your PC is very very very likely to be infected. Avira basically does not have off-line behavior blocker.
For Free version, no. But you will see in-product ads that cannot be disabled.
Nortonization here means the addition of Cryptomining feature, and it's nothing to do with the privacy protection.
Yes, freemium model will be kept.