Whenever we let one of our cats out for the first time we'd do so right before feeding time. Make sure their bowls inside are empty or taken away after breakfast then about 10mins before dinner let them out. Go out with them if you can the first few times, then after 10mins start calling them for dinner back inside. I think we did this for about a week then they were on their own!
I agree.. Even now my cat is 8yrs old and because I don't like him out at night I try not to let him out after dinner time as it is always a lure.. Don't use food as a bribe to get them in though if you are not going to feed them.. Cats are smart enough to figure that out..

And yes they will occasionally go to the toilet where they shouldn't somewhere new.. Just a territorial thing.. And as for peeing on your Ds's bath toys maybe that was just because they couldn't find the toilet and it was close to a drain? My cat pees in the bath if his litter isn't around.. Or it could again be a territorial thing..