Running too cold

Well I've come to realized that my car is running to cold. It'll only get two like 160ish well, at least that's what the temp gauge says.

So a couple questions.

How accurate is the gauge it self?

For some reason I thought I read somewhere that there was more than one temp sensor? Is that true

Also I've been having a rough idle and rich smell for the longest time. Which I'm assuming is the computer thinking it's colder than it is and pumping in extra fuel.

So if it is my problem, is there a way to test the temp sensor? I have a laser inferred temp gun should the block be around a temp? Or the rad?

So assuming all sensors check out and the engine is actually that cold, do I have drain all the fluid to change the t-stat? The coolant is only a couple months old and am on a little bit of a budget but if it needs it then it needs it. Don't want to get coolant all over the engine bay.

Thanks in advance!

Running too cold