About the topbar menu, if you edit the menu's module by changing (under the Module tab) CSS/Superfish to y and Use Bootstrap menus to n, then the menu items will wrap to a second row; at least that's the behavior in my local branch 20. Your menu does have quite a number of items for a page top menu, and apparently the Bootstrap default design is to display them in a single row, without wrapping.
I haven't looked into the footer issues yet.
Based on your comments, I could manage to reproduce the look & feel of version 18.4.
I still experienced those database error messages I mentioned before, while upgrading to 20.1.
Bunch of these for a lote of tables:
"Error in unknown patch script
ALTER TABLE `messu_messages` convert to character set DEFAULT COLLATE DEFAULT
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DEFAULT' at line 1"
and a couple of these:
"ALTER TABLE `tiki_pages` CHANGE `data` `data` mediumtext COLLATE utf8mb4_unicode_ci
Column 'data' cannot be part of FULLTEXT index
Error in unknown patch script"
I'm not sure how important are these...