Each couple is different.

If one has been (or is) in the military, then separations are expected. The bigger issue there, as with most separations, is how the 2 act when they get back together. One has taken over all the daily household stuff (mow the lawn, wash the car ect) and usually the other wants his/her responsibilities back the minute they step back into the picture.... These things work themselves out over time, but in the near term it can be stressful.

Like them, communication is the key. During separations one needs to keep the communications flowing. You both want/need the other to express how much they miss/love you. So do it....text, calls, messenger....

Directly to your question: I don't have a minimum or a maximum. I can tell you that my spouse travels overseas once a year or so and sometimes stays for several months. We stay in constant communication.

I don’t know, but when I was married, we had at least one phone call a day, and maybe a text. That was after 10-years of marriage, seeing each other daily, and our marriage was unhappy, but we had some contact every day even in a bad marriage.

Each couple has to make their own rules. He may be acting more distant if you told him you don’t like clingy.
My advice… don’t pretend you don’t want to call him or text him if it’s after work hours, just call and ask him out.

It depends on your comfort level and whether this in an LDR or not. In an LDR, I wouldn't expect daily contact, but when you live with someone things can get weird very fast if you neglect to talk on a regular basis.

If you don’t live together, once or twice a week is about normal to see each other…

I think 3 or more dates a week is a relationship

Less than 3 is just dating.