estimation for utility costs?

Impossible because utility prices vary greatly among regions and time of year and even time of day use. Electric rates vary from about $0.12/kw to $0.34/kw. Gas for cooking varies as much depending upon the season, etc. I would budget about $0.12 per square foot of floor space until you get a handle on the utility bill. My utilities run about $0.12 per sq ft of floor space for MY area of the country and the season.

My experience is that electric rates are higher for multi-fuel homes (gas & electric) vs total electric homes.

You will need heat in Ohio unless you emigrate to warm climates in the winter.

Not at all...

Depends on the square footage of the house, the floorplan(closed rooms or open floor plan)

But if it helps any, I used to have a 2 story with 3 bedrooms as well, in the summer running two a/c's cost me about $125 a month, winter with electric heat was anywhere between 200-300 a month

Going from living on my own with my 3 year old to living with roommates, it mostly depends on the people occupying the house. When my son and I were living alone the electric bill averaged $60 when less efficient people moved in the bill went up to about $110 so it depends on the person. I also keep all my electronics on surge protectors, tv's on timers, and use energy efficient bulbs