pstake: TF-5 is approximately neutral (actually slightly acidic) at pH 6.5. pH7 would be exactly neutral. TF-4 is alkaline.
I'm not a chemist either but basically it is easier to wash an alkaline solution out of the paper than an acidic one, and standard commercial rapid (and non rapid) fixers are acidic.
Regarding fixing time, generally yes film takes longer to fix than paper.
Overfixing prints can increase the required washing time because the longer time in the fixer means there is more time for the fixer to penetrate the paper base. This is why the Ilford archival sequence with calls for a rapid fixer, requiring a relatively short fixing time - which means washing can be faster.
Another reason to avoid leaving either film or paper in standard fixers for excessively long periods is the fixer will start to bleach the silver in the developed image.
But remember, underfixing is bad. Better to slightly overfix than underfix. Best is to do it properly, which is why it is important to use fresh solutions for the recommended times.