If you are forwarding calls from your home phone the number of the person calling you will show up on your cellular phone the same as if you were taking the call on your home phone.

Yes you do use minutes if you are talking on the phone. The only time I forward calls from my home phone is on the weekends when the minutes are unlimited.

Conversely if you forward from your cell phone to your home phone you are charged minutes off your plan. If it's the weekend and you have unlimited minutes then it doesn't make any difference.