http://www.hort.purdue.edu/newcrop/m...sk_tomato.html
Above is the best website I know of with regard to almost everything you need to know about growing tomatillos.
Some quick answers:
As stated above tomatillos ( Physalis) do not cross with tomatoes ( Solanum)
Tomatillos are self infertile so you need to grow at least two plants to get berries, for that's what the fruits are. Note in the article that pollination from another Physalis sp can occur within a certain distance, but best to plant your at least two plants next to each other.
Not for fresh eating, rather, for salsa's and similar.
And there is a place below on this first page here at Tville in the other veggies and fruit sections for just Tomatoillos if you didn't see it.