Hi, I personally think that the tour company would not drop you off at Aguas Calientes but back at Cusco, after the trek. Aquas calientes is a good drive from Cusco. If the tour is full there is not much room on the minibuses but no harm in asking the tour operator about your backpacks or you could ask the hotel at Cusco to keep them until your return. Good luck and enjoy your trek.

I'm sorry, I don't know if children are free. You could contact Kaypi Tours (the company I travelled with)

We spent about an hour at the lake. Time is short as the bus ride is long to get back to Cusco.

Hola depende de el estado físico del Niño , es una laguna maravillosa pero realmente se necesita un excelente estado físico para subir a la laguna humantay.

The road is very twisty with lots of switchbacks - I was very glad to have a good driver. A group excursion is very cheap (likely includes breakfast and entrance fee - you might consider that option.

My guide, his wife and (almost) 3 year old son rode into Humantay with me. We walked back out. I walked (very slowly and carefully) while the little guy had no problem with the altitude and ran most of the way. When he got tired, his mom tied him to her back and he slept. If you are going to hike in, I suggest you go early before it gets too hot and before there are too many people. Don't miss this adventure - it is spectacular.