Question 1: Is there a way to have SVN normalize line ending on commit by itself?
It seems svn:eol-style is set on this file. If you set svn:eol-style on a file (to any supported value), Subversion requires that the file have consistent line endings before you commit it. You or your tools must do this; Subversion will not.
If you do not set svn:eol-style, then Subversion does not check the line endings and lets you commit whatever you want, so if for some reason you want inconsistent line endings then that's how you can have that.
Question 2: Why txn-protorevs aren’t being cleaned up properly?
I don't know what's going on there. Do you have any hook scripts? Maybe one of them is programmed incorrectly.