Pretty much just that. Even a single upgrade is enough.

It does, energy upgrades tie hand in hand with gas consumption.
If you don't up the speed as well it really wont use much.

Up your processing tier (so shards or crystals) and it will eat the gas for breakfast.
I do admit to not playing around with just the standalone chamber though, I only use elite factories.

This is true, but see #1874 for more.