I have several contiguous questions regarding the possibility of Software Collections repositories distribution:
Is it allowed to sync, sign with a PGP key and distribute specific Software Collections repositories?
Which Collections do you speak about? There are basically two kinds: Red Hat Software Collections (RHSCL) available to all RH subscribers and downloadable from RHN. Your license agreement apply to those package, i.e. you cannot redistribute binary packages, you can handle source packages according their license. Then there are comunity version of Software Collection (SCL) available at softwarecollections.org. These are free to distribute. I just realized it is not stated anywhere on the web explicitely. I will fix that soon (I'm softwarecollections.org admin). AFAIK all of those packages are license under GPLv2+.
Are there any conditions/rules under which the repositories can be distributed?
With SCL you can do anything what GPLv2 permits e.g. copy, distribute, modify.
Are there any plans to introduce mirrors? If yes, under what conditions/rules a Software Collections mirror can be brought online?
No plans for mirrors. Feel free to setup your own mirror. We have plans to allow rsync, but so far there was technical limitation, which did not permit it, I hope it will be resolved soon.