This is good information, and nicely posted in the support forums
We need to use these forums more for user to user support like this!
To answer your question:
I would set the max_execution_time to maybe 60 seconds, which will help with the backup feature once its up and running again. otherwise I would leave alone at 30. Oh, if you use the mailin on the forums you might want to set to 120
upload_max_filesize set to whatever you want to set as a limit for your site! LimitRequestBody might also have to set as well to a larger value.
memory_limit 16Mb for a starting out TikiWiki maybe raised to 24 or 32 on an established one like tikiwiki.org.
Lets hope that your findings help many more of our Tiki users!