If you don't care for the taste, you have two options.
Optimized for comfort
Start buying uniform size fish. Cook it through using a guess for the time as a starting point. You just pull the fish out, try eating it, and if it is raw in the middle, you put it back into the pot. Record the time the fish took until it was cooked through. The next time, ...
The problem will be one of temperature difference. The outermost mm of your salmon will thaw immediately but the innermost one will still be raw.
Some meat thermometers will work in water but i doubt that they will be accurate in a thin filet as they are mostly for use in large chunks of meat.
So the only good way to check fore done-ness is to cut the ...
Common "rolled" oats are flattened into fat disc-shaped units; "quick" oats are rolled and then further sliced thin to cook faster. "Steel cut" oats are just cut into small hard pieces like short rice grains.
For quick oats, add about 2:1 water to oats, and cook until done to desired softness, which should be a few minutes. For rolled oats, cook longer and ...
If it is instant oatmeal, just add boiling water (ratio water to oats 2/1) and let it sit for 5 minutes. If it not instant, same ratio of water to oats, boil for 5 minutes while stirring, remove from heat, cover and let sit for 5 minutes.
I googled "how to cook oatmeal" and found several similiar ways.
No one seemed that interested in answering the part of question about cooling time. Luckily, someone else has done a wee experiment and put it on their site:
They also used a cooking pan.
According to their data and this excellent answer on Coffee SO which says: