kim, she prob is ok
likely she won't feed incorrectly. reducing the choc intake might be a good idea tho
if the colour is similar to the green on this website, it might be from oxidasation (like an apple going brown after you cut it).
if you've got a cold, you're creating antibodies, so not likely she'll get one
length of time on the breast is no indication of anything - so called snack feeders are normal, long feeders are normal
a baby who feeds quickly is getting the correct amount of milk for them, as is the other sort. they all take the bulk of their feed in the first few minutes (once bf is established, sometimes from day dot, sometimes it takes a few weeks to co-ordinate the suck/swallow) . a baby who feeds often may get more fat in their diet than one who feeds every 3 hours. but unless you have oversupply, lactose overload is unlikely (tho not impossible of course). it should be called 'not enough fat' tho
one possibility is secondary lactose intolerance (i'd look at this as a last resort tho)
Australian Breastfeeding Association - Lactose intolerance and the breastfed baby