Overall heat of the map

What do you mean? There is an ice maker / liquid cooler.
It's also a gas cooler so you can just loop your atmosphere through it and connect it to a switch to have a controllable air conditioner.
It's called the thermo regulator. You pump in whatever gas you want, and it comes out colder.
You can pump in steam and get ice. You can even pump in oxygen and get liquid freezing oxygen back.

As for the meal lice, there are lots of benefits to eating the better meals if you can replace water.
They get more full, it's more efficient, and they will stress less, meaning less vomit, and less destruction.

There are a few ways to replace water, such as steaming up contaminated water (which you can produce endlessly)
to make steam, and then cool back down to regular water.

for replacing seeds: disable/lower priority
for overal heat building (making steam not help  I recomend puting plants in far end of asteroid near cold stones. It helps a lot.