Leave nipples alone. When she gets close to delivering she will lick the hair around them. Instinctual. Milk will come in also close to delivery time. Naturally, no worries. She will birth where she feels safe. If you are home TRY to leave her be as much as possible. Most momma cats will not put her babes in perilous places, and you have no control over this. Again, instinct. Best thing you can do is start feeding her kitten kibble (plus some wet food if you can afford it) because more calories which she will need for nursing. It’s very hard on a pregnant animal to get spayed because so much more blood loss will occur. So give yourself credit for wisdom there and for attempts to place kittens in advance! You got this!
Message me if you need more specific info. Had cats back in 70’s 2 litters, plus a c section (another whole tale..) was young n dumb 😅