What is the ratio for soft polenta? I want to cook a soft polenta. I would like the consistency to be like pudding - just firm enough to hold a shape (it doesn't flow out of the spoon if you take a heaped spoonful), but not firm enough to be cut into pieces. My ingredients will be cornmeal (not cornflour; it seems to be ~600 µm grain size), milk and olive oil. I am looking for the correct ratio by weight to achieve this consistency. 

If you don't have a ratio for this case, but know a ratio for a similar polenta (e.g. cornmeal + stock) which gives this consistency, I'd be glad to know this one too, I think I can get the tweaking right by myself.
Yes, it depends on brand, humidity, etc. My local variety is 1:4 to 1:4.5 (polenta:water) to get to that softness level

Add nothing else until you have the polenta at the desired consistency and softness