Well I'm not really sure how I can explain how much mess a guinea pig makes in a day so hopefully another member can explain it to you better, but it's a decent amount. It also depends on the guinea pigs. My guinea pig likes her litter box, while my foster pig goes everywhere. They make the same mess on both fleece and bedding it might just look messier on fleece because sometimes the bedding can hide the poos. Although on bedding their pee is more noticeable than on fleece. You can get darker fleece so the poos don't show up as much, but I have found that it's a lot harder to sweep up the cage with darker fleece.
As for the cages smelling, they aren't going to smell like flowers
They will have an odor, but I wouldn't say it's a bad odor because it smells mostly like hay. The more you sweep up the cage, and the more often you do full cage cleanings, the less the cage will smell.
Last thing, I wouldn't recommend letting your guinea pig play with the female across the street. One reason is it's not very nice for your guinea pig to have a friend for like an hour and then take them away from each other. Also, it's stressful for guinea pigs to meet over and over again because they have to go through dominance again every time they meet. Either get a guinea pig that doesn't like others, like I did, or get two guinea pigs. If you can only get one guinea pig, rescues have multiple guinea pigs that aggressive toward other guinea pigs and therefore are singles. That's what happened to me. My parents only allowed me one guinea pig so I went to my local small animal rescue and a little single piggie picked me
I've tried her with lots of guinea pigs, but to this day she still hates every pig.
Hope I helped!
EDIT: Looks like everyone beat me
By the way, my guinea has pooped at least 10 times in the last 2 hours. Just for reference.