So can anyone kindly enlighten me how a house blessing is performed,
In Greek practice, the rite used outside of Theophany is the "Lesser Sanctification of Water"
The Priest will usually bring everything which is needed, but it's always good to check with him. Also, the Basil branches mentioned in the link are a Greek practice, Slavic Churches use a special sprinkling brush.
if I'm supposed to prepare dinner for our priest,
I would certainly invite him. Also, a donation to the Priest might be a good idea. Our rites are long and involved and our Priests often have to travel far to perform them and they have families of their own. "A worker is worth his salt" as the Scriptures say.
if I can have friends and family present,
Absolutely! It is a joyous occassion!
and anything else useful to know.
Ask the older people at your Church. They love to share the local customs and traditions and pass them on. They are "the fifth Gospel"!