Secure Bike Parking.?

I have been commuting to work year round for over two years. My office will
be moving soon. Presently, I lock my bike to some racks outside of my
building. However, as a result of the moving process, I only just now
learned that we've always had some secure parking available in bike lockers
in an underground garage and that they will be moving those lockers to one
garage at our new office location and also building a bike room in another
of the new above ground garages. So I'm considering using the secure
parking, although free use of outside racks will still be availabe at the
new building also. It's $50/yr for the secure parking, which I find to be a
reasonable and comparable price after looking at a survey for bike locker
rental fees in different places that I found on some website that I can't
remember now. So a couple of questions for anyone who has used secure
parking or bike lockers.

First, do lockers make it okay to leave your light system on your bike? In
the past I've taken the light in and left the battery or taken the battery
in and left the light. But when leaving the battery out during some of the
coldest winter days, I believe that may have been bad for the condition of
the battery or the contacts, so I've taken to always bringing the battery
and the light inside with me, especially since I'm now using a light system
that costs more than my bike. I'm in the Washington, DC metro area, so I'm
wondering if a bike locker in an above ground garage would be adequate for
protecting the battery from the elements. If I didn't have to take the
light system off my bike, it would save me a few minutes and I wouldn't have
to worry about lugging it around in my bag.

Second, might the bike locker help protect the bike from the elements? If
parking inside might save some wear on my bike, then that might speed my
decision to shed $50/yr.

I did mention a bike room, but that won't be available for a while and it
will be a SHARED room, so I'd prefer to use the bike lockers if I decide to
use the secured parking, and that's why questions are about the bike
lockers. But if anyone's had good experience with or know of some
advantages to using a bike room that might not be obvious, I'd be interested
in hearing about it. Thanks in advance for any answers.