Friends and Family at Homebirth
To the best of my knowledge there are no laws against homebirth in any state. The laws that prevent homebirths are the laws that keep midwives from practicing midwifery without a license. So, if your friend wants to help you have an unassisted birth, there shouldn't be a problem.
Most homebirth midwives are as familiar with private couple only births as they are big family and friend births. Simply explain your plan to your midwife. She may have suggestions about how to make the presence of others less distracting for you, or jobs that can be done so everyone who attends your baby's birth can be a part of it.
There are no hard and fast rules about having your children with you at a homebirth. It depends on how comfortable you are with the idea, and how comfortable your children are with the idea. Some families keep the children in the house, but away from mom while she labors, so they can see the new baby right away but not have to be there for the whole labor. No matter what you decide about your children, be sure you have an adult you trust to care for the children. Labor can be a long experience for children and having someone to play with them, get them meals and answer their questions can make the event more enjoyable.
It's a thin line, but you should also be able to hire a doula to help you at an unassisted (without midwife) homebirth as long as the doula doesn't perform outside the scope of a doula. The scope varies slightly with different organizations, but basically the doula is only emotional and physical support, she doesn't do any medical stuff. I had two doulas with me when I gave birth at home without my midwife. They were both friends of mine who came instantly when I thought labor was trying to start. I felt foolish as nothing seemed to indicate progressive labor, and was ready to tell them to go home when things suddenly got pushy. One friend called my midwife and one stayed with my husband and I while I figured out what I wanted to do. They basically watched as I pushed, but I am so glad they were there after my son was born. They helped me get cleaned up and comfortable again before they left.