We keep it in the shade , black out the windows and never had a problem. Most of the time we fit LVT so can’t have direct sunlight on it while fitting it.
No it doesn’t as that weakens it and you get a soft finish.
Most bags will have a the max and min of water to go on. 4.5ltr - 4.75ltr. Never go above that.
Should have used primer.
Should have mixed it quickly. Someone mix and keep them coming and one putting it down.
Never heard of that compound so can’t comment if it’s any good.
The best wet edge compound is ardex k40 flow
It prob won’t have one and even if it did it would be perished now. So yes a Dpm sandwich will sort it out.
Give the floor a scape with a blade scraper 1st.
Then na straight to it.
You only need to do one coat of liquid Dpm.
Fill the hole in with sand and cement on a visqueen sheet lapping up the doorframe.
Get it close the height of the main floor.
Let that set.