can it be said without a minyan? what about on shabbat during blessing of the children? what about by a female? -should the hand symbol be made? thanks!

A non-Cohen may not get up in shul and say the Birkat Cohanim (priestly blessing). However, there is no problem for a man or a woman to say the pesukim of Birkat Cohanim. This is because one who says the pesukim does not mean to say the blessing as a fulfilment of the Cohanim's mitzvah. Rather, he or she is saying it as as a prayer, usually to their children. The fact that it is said without raising ones hands in the air like Cohanim, and it is not said during the davening like Cohanim do, makes it obvious that it is not a replacement for the public prayer of the Cohanim, but as a private prayer. There is nothing wrong with that, and is even meritorious. The hand symbol would be forbidden as this is only done by Cohanim and in a minyan. (Biur Halacha 128, 1, 'dezar') It is indeed a beautiful minhag for the father and the mother to give their children a blessing with the Birkat Cohanim on the night of Shabbat, and should be encouraged. All the best