It's in present tense- which I don't write a lot of- so, bear with me here.
Your first sentence is the intro to the rest of the story. It can make or break a novel right out of the gate. You want something with a punch that sets the tone for the rest of the chapter.
I might, totally a suggestion, say:
Mealots were a vicious lot.
(And then describe them.) something the MC hates most about them works well, like how much they smell when their heads are removed or something.
Remember to keep to present tense if you are sticking with it. In the second paragraph, exuded should be exude.
"Why is it every time we build a barricade there is a counterattack?" Olaf asks, glancing at Hank. (I do love this line of dialogue. I can hear the exasperation.) Now, the tricky part here, is that you've described the sweat and then repeat that Hank is sweating. All I know about Hank at this moment is that he sweats. Who is he?
Then suddenly we have Omer- and we've headhopped- unless you are going for 3rd person omnisicient- I'd suggest Olaf being envious of Omer's duster(because I am, lol) and you can still keep the line about where the duster came from. This tells me a little about Omer.
Why does Hank stop sweating? Have the man take a deep breath maybe? This adds description- and possibly have him doing something to show he's a mechanic? What is he working on?
Introduce the men much slower, and with an action, so the reader can ground themselves in the characters. I want to know them. Showing- is giving me an action, like you did with Omer- he's making a potion- that tells me so much about him, along with the bit about the coat. I know more about him than I do about the others, until we get to the italics- and then you're telling the reader who is who and who does what.
So far, Omer is the only character I know anything about, as if you are more comfortable in his head than the others?
Does this help?