For the Column 'review_round_id' cannot be null
messages, see Error Upgrade 2.4.8.2 to 3.1.0 - #16 by Adriano_Jose for a discussion and solution.
The other warnings suggest a few missing files and database inconsistencies, but I don’t believe they are causing the upgrade to fail.
Regards,
Alec Smecher
Public Knowledge Project Team