so has anyone found all the location for the scenes not in the CG room?
AFAIK, the scenes are available after you get extremely high Depravity (100+ I think), where basically Makina becomes a "slut". Any NPC with a dialogue bubble with a heart above is available, but for the options I know of/found:
The flirt in front of the bar, the Dirty Inn (basically several of them are available after spending the 20 gold. You get a sex scene and a Rest), the cuckhold husband (one of the houses with the red haired man complaining that his wife is cheating on him), a guild member in the barracks, the drug dealer in the Underground Market (same guy for the drug dealer scene), the Underground Weapon Shop dealer (also a repeated scene) and one with the blonde haired adventurer in front of the arena.
There's also mini-scenes in the brothel and with Mohawk-Guy you can do once per day.
Where am I supposed to go after finding the starving knight in front of the entrance of the ruins ?
Keep going deeper in the ruins. It's the only way to progress the main story.