1. KLM does not have a dedicated gate. Gate 224 is the closest to the Skyteam lounge but the international gates run the entire length of the terminal so you could have quite a hike.

http://www.ataturkairport.com/tr-TR/...ents/gidis.pdf

2. No idea, not been in that lounge yet, but as IST is pretty much a 24-hour operation and has a lot of nighttime activity/early morning flights, you're bound to find something approaching breakfast even at that time.