I'tikaaf

Q: When sitting for nafl i’tikaaf, is it necessary for one to be fasting?

Q: Is it permissible for a man sitting for Sunnah i'tikaaf to use a cell phone to check on his family at home and to see to their needs?

Q: I was reading something on one of the islamic forums on the net. They were talking about their musjid not having facilities for women’s I'tikaaf. When I mentioned that as far as I know, women are supposed to observe I'tikaaf at home, a lady replied: If a woman wishes to perform i'tikaaf, then she should do so in a masjid, so long as there is no danger in that (such as free-mixing and complacency regarding the hijaab, etc). Please explain if this is correct.