One of the red flags for me is that they only gave you ten days notice. You know more than ten days in advance that you're going to a wedding (especially one that you're travelling to with children), so were you a fallback option after someone else said no?
That stuck out to me too. Surely they knew ages prior to calling you that they were going to be attending the wedding. What if you'd said no to accommodating them?
In this situation, I'd give them a pass on the not spending too much time together thing, as they were upfront about only using you for accommodation. However, they don't get a pass on anything else at all. They were flat out rude.
They should have paid, or at least offered to pay, for the evening meal, as a thank you for letting them stay.
I wouldn't dream of staying anywhere without taking a mattress protector for my (then) 4 year old.
My kids were/are early risers, but when we stayed away from home, they were expected/told to be quiet until the host was up and about. Usually they were kept in our room with us, or if we did go elsewhere in the house, it'd be to one room for a quiet activity. I'm not an early riser by nature, but when staying with someone else, I ensure that I do get up with or before my kids, so as to supervise them properly.
I always asked what to do with dirty nappies, or if I did forget, I'd put them in the scented plastic nappy bags and place them in an outside bin. I never left dirty nappies lying around my own house, let alone someone else's.
Pulling the furniture apart and/or leaving dirty stuff around the house - what planet are these people from that they think this is acceptable behaviour in someone else's home?!?!?!?!? Let alone not even offering, or better yet rectifying, the situation.
Prior to leaving, they should have gone around the house, tidying up every bit of their considerable mess.
They definitely should also have contacted you once they were home, to (A) let you know they arrived safely, and (B) to say thank you.
It'd be a dark day in ehell before they ever crossed my doorstep again, even just for an afternoon visit.