I have a home daycare and I use vinegar and water or just hot water and soap.
As far as frequency goes, I clean them as needed or once a week. Sometimes I take toys out if kids are sick. For example, if kids have a cold I will put up the play food, cups, utensils etc... because those most often go in mouths. When I say "as needed" I mean that if I see a child put a toy in their mouth, it goes in the sink to be washed, or if there is obvious yuck on a toy.
As for spreading germs, they are just out there. Usually if a child comes in with something, most of the kids are going to catch it because kids sneeze and cough without covering and they rub their noses on their sleeves when they are little. We practice frequent hand washing and teaching covering (coughing sneezing into the arm rather than on hands).
All kids have to go through building their immune system, which usually equates to being sick with a cold about once a month and 3 or so flus during the sick season for the first year or two in a group child environment. That's true for daycare, preschool or kinder... whichever they begin first group care.