"2 RAF personnel killed in mid-air collision" today

[cats_five]

1) Assuming the glider was equipped with FLARM, should it alert off of a regular transponder like the tutor, or just off of other FLARM equipped aircraft?

Flarm won't set off a transponder, just another Flarm. See the Flarm website:
www.flarm.com

Takeup of Flarm should have got a boost amongst XC glider pilots now that some of the units are FAI-approved flight loggers, which means the traces from them can be used for badge claims and the like. When I brought my logger 1 1/2 years ago that wasn't the case, and also Flarm has come down in cost a bit since then.

2) We know that some composites can be safely painted, but does fiberglass have characteristics (unlike other composites) that make it unsafe or unwise to paint in contrasting colors?

The issue isn't with painting a glider - a Ventus or Nimbus (sorry can't remember which) at my club was refinished with car two-pack last year and looks great and many others have been refinished with two-pack paint. Both are offered by the East European workshops doing a lot of the commercial refinishing in the EU.

The issue is with a non-white finish because it heats the underlying structure. If you feel the top of a white glider wing it's cool, even if it's been in the sun all day. If you find a glider with (for example) red wing tips they will be warm. You can feel it with washing on the line as well - a pale teeshirt will be cool, a dark one warm.