1991 190e 2.6 manual

I noticed it was a little difficult to get it in reverse a few times, then after a few days I tried to drive and putting it in reverse was very hard, and hand to grind it to get it engaged. First and second were grinds too. I fought hard to get it into reverse twice, first three times, and second twice, had to really fight to grind through to engage it, but I had no choice.

When I press the clutch it's just free until I get to the very last 10% or so, it's like it's not catching anything until the very bottom, and then probably not enough.

Questions/best guesses:

How much damage did I do grinding into 1, 2 and reverse a few times?

Does this sound like a clutch, transmission, or something else?

How do I troubleshoot? Is transmission fluid the first thing to check or is this definitely indicative of a clutch problem? I think on the manual you have to get under the car and open the "in" hole and if nothing comes out it's low so then you drain through the "out" hole and refill with some kind of pump?

Thanks for your help guys!