As eyepaq says - it's for holding executable "program" files. search engiens don't need access so it gets blocked. If it's empty you can even remove it.

doesn't seem to, no

Not having the numbers would probably be less confusing than having numbers that might later duplicate.  If you can produce the news sitemaps (and keep them accurate & up to date) the unique numbers are not technically required for Google news listings.  So if they are hard to add and you are confident in your sitemaps it shouldn't be an issue.

If you are less confident in them and being listed on google news is a big deal for you then try to get them added.

I do this on a few domains and it works well and without a problem.

You should ensure that logged out users (and those who's status you cannot verify) are not directed and then only direct the logged in ones.  That way any crawlers (and logged out users) that come along will not see the redirect at all and just read the url that they requested.

This is slightly different logic to.  It sounds like you might be  testing all users and redirecting them to one of two different URLs - neither of which is the one they requested.  This would be undesirable and would cause the 302 that you describe.

You're welcome.  Let me know if they come back with any questions.