Can any learned expert tell me ... the ideal way to worship Hindu deities inside a home?

I have 2 Ganesh idols and 1 Ganesh coin.... in addition to other idols (Brahma, Krishna, 2 Laxmi coins, Bhavani). Does it matter if I have 3 idols of one God? (Since 3 is not considered good no. in Hinduism...)I was presented the additional idols by my relatives.

Is the presence of "kul-dev"....i.e. "traditional family" deity idol necessary at home?

Confused...