Many varieties of peppers normally develop dark - almost black nodes and stem joints. It is normal. As to the blooms falling off - it is a weather-related (most likely cause) condition called 'Blossom Drop' and I linked the FAQ on it below. It discusses the causes in detail. Using that term you can also learn a great deal about it on the web and there are lots of discussions here too that you might want to browse through. Dave Here is a link that might be useful: Blossom Drop FAQ

I'm in the San Fernando Valley and a few of my unripe pods are getting sunburned too. The chile Arbol are turning red overnight and are seedless,the Italian Gourmette are going from green to yellow/red faster than the pod can grow. The smaller pods on some plants are half dried each day. My plants have total southern exposure and some are under greenhouse cloth but still the heat is making them go crazy. Stuff like my Trinidad Scorpions and 7 pot love it,growing like crazy.Some love it hot and sunny all day long. I only lost a Billy goat,Big Sun Scotch Bonnet and a Hot Portagul so far. They just were too small to take the heat even though they were under the greenhouse cloth. I think I need to put some plants in bigger pots.The soil gets too hot I think. I have a lot in 2-3 gal. containers and when I go out to water the soil in them is pretty hot (even when damp) when I stick my finger in it to see if it's damp or not. Other then having pods turn red before they grow to size I only have a few that are getting sunburned. Mostly the ones that grow pods out in the open not under the leaves. I'm going to put up some more cloth that has a higher sun blocking rating.I'll also put some side pieces up that let less sun in. I don't know if it will help as it might just make for less air circulation more heat retention.I guess I'll find out. Since when did Aug. come so early? :( At least it's not 40 degree nights like a few weeks ago (80 degree days and 40 degree nights).

I've been gardening for 25 years or so and have never heard of ants causing flowers to drop. I never stop being surprised by new info though, so never say never is my motto. Some likely causes of blossom drop include excessive heat, overproduction of flowers, no pollination (self or otherwise) and maybe nutrient problems. Excessive soil dryness can also cause it but you would have noticed other symptoms and you mention the plants look healthy so I doubt drought is the cause!

I have one bhut that's a monster of foliage without one single pod newer than the last two months or so anywhere on it. Five feet wide, full sun, growing like a weed, teeny tiny flowers, no interest in setting fruit at all. I took hedge clippers to it and two days later it was sprouting new greenery everywhere, so health is OK. Still setting no fruit. It'll happen, just not yet. Here we generally get the big end-of-summer weather break about mid September; then I'll worry.