Just the usual difference between simple present and present continuous.
Simple present gives a fact that is generally true, and not implied to be temporary. Present continuous is for temporary conditions.
"I count on you always"/ "I'm counting on you now, in the current situation".
I told her to light the lamb when it gets dark.
Means that you have told her to light the lamb whenever it gets dark.
I told her to light the lamb when it got dark.
It's in the past and the action is done and finished.
If the situation will be true for the entire duration of the vacation, "We eat..." fits a little bit better. If it's a temporary situation within the vacation that you are describing, the present continuous fits better:
"Currently, we are eating in a restaurant every day, at least until we find a room with a kitchenette."
But it makes ...
In order to pay tuition fees and other expenses he works / is working four days a week in the university kitchen, while in the university holidays he does a part-time job.
I'm not sure about the work / is working - frankly they both sound fine to me. Works perhaps suggests that he'll continue working four days a week in the kitchen throughout his degree, ...
I agree with the comment. The better choices are "is causing", because it refers to a recent change looked at as a progression, and "don't realize", since realization is a threshold question here (they do or do not realize).
They're both grammatical, but the meaning fits better with "causing" and "realize".
You could ...