I use hoops always. This is a very personal decision as others use lap stands, etc. It is just a personal decision. The material goes over the bottom hoop. Have that top hoop with the screw somewhat loose and slip it over the material. Start tightening the top hoop all the while making sure your material is staying taut. Just keep tightening the top hoop again keeping the material taut. When it is tight enough (it should not be loose) make sure that screw is turned very tight and make adjustments to the material. Don't be afraid you can't do it cause you cannot make a mistake. When you ask about size of hoop, it is personal. I usually use a 6 inch or 8 inch hoop. You are worried about what that will do over time. Nothing. I have worked an afghan using a hoop just rolling up the top and the bottom so they don't get in the way. I would remove my work when done for the day to help keep from leaving hoop marks. When you put it on or take it off the hoop, just be careful. When you are through, use a little Dawn in cold water to get any dirt or oil from your hands. I put a towel on my ironing board and with my work a little damp press it UPSIDE DOWN. Those stitches will pop right up. If I have told you enough or told you something wrong, another stitcher can give you his/her ideas. Good luck and if you have any questions that I didn't answer, just post again. By the way don't forget that the center of your material needs to be the center in the hoop. Most importantly, DON'T BE SCARED, YOU CAN DO IT.

For large stuff, I use a scroll frame. I like my projects reasonably neat to work on...all that extra fabric, even rolled and clipped, throws me off my game. If that 25 is for the width, you need 26" scroll bars. "Stretcher bars" are the vertical side bars that hold the scroll bars apart. These come in different lengths...6, 8, 10. I like the 8", but you'll have to make up your own mind about that.
I'm amazed nobody suggested q-snaps...our numbers are depleted...I hate them for a number reasons, most relevant is the size of the grip and the clamps.
If you have questions, post them! Somebody will come to the rescue...😊

I sure hope you mean 25 inches by 36 inches and not feet - as your post shows! I hope it was a typo and should be 25"x36". I about fell off my chair when I first read this and thought feet! Yikes that would be gigantic. I still use a hoop - even for my large projects - I have one that is 30"x36" (the cloth). I use a 10" hoop and it works for me. You just have to decide what works best for you. Many people like scrolls, but I am not one of those (they get cumbersome to me).