I think that when is badly pronounced
Sounds pretty much the same as how it's said here: http://en.wiktionary.org/wiki/quand
Yes, I thought with most of the 'ils/elles' form of a verb you don't pronounce the 'ent' ending so it sounds pretty much the same as the 'il/elle' form of the verb, e.g. 'il mange' and 'ils mangent' sound the same.
meurent almost sounded like "mer" to me, so I got confused, but I think that might just be me hearing it wrong.
Yes, I put 'Quand mer le rose' as I wasn't sure. Tricky without context.