I would try giving him an additional 1/2 can of food twice a day - if there is a lot left over then the one can is probably sufficient.
As far as letting him roam the house - if your kids have lots of toys left out I would not let him roam unsupervised... best to either keep him safely sequestered or teach the kids to pick up their toys as soon as they are done playing with them.
As far as letting him roam the house - if your kids have lots of toys left out I would not let him roam unsupervised... best to either keep him safely sequestered or teach the kids to pick up their toys as soon as they are done playing with them.