So I will start off by saying I love putting stuff together so while the instructions weren't explicit, if you have the room and sort the pieces prior to starting you will have an easier time. Next, I recommend not completely tightening the boards all the way until you are confident in your placement and spacing. Give yourself the necessary spacing for minor flexibility and adjustments. I purchased the largest wheel. Put it together by myself in less than two hours, I am 5'4 and about 140 for size reference. If you have a bad back get friend to help you stand the wheel up and flip it. As far as getting my three cats running on it, my two girls love it! No training needed, scratch the carpet and away they go! They run on it daily. However, my 20lb boy that this was purchased for prefers the human treadmill with mom. So while not a complete waste, my chonky boy is not using it but my little girls love it! They do scratch the carpet heavily, it is showing significant picks already. I will need to replace it but my three are heavy scratchers. I am looking at the adhesive carpet tiles as an option. The noise is a whirring sound almost like a dryer on spin, very minimal if they are going full Usian Bolt. You can lock the wheel during the night but you may get hateful looks in the morning. This was 100% worth the money spent! I hope this is helpful!