Here's my experience. I was a SAHM for many years. When my ex and I separated, he agreed to move out but threatened me saying he was going to get the house and full custody of our 2 boys still living at home. At the same time, he was trying to get me to work out our divorce on our own, without attorneys. I found a good attorney and quit talking to my ex. He continued to send me long rants and threats. It was cumbersome communicating only through my attorney but it was the best thing I ever did. It took over a year for us to agree on a settlement, mostly because my ex was representing himself and made things difficult to try to wear me down. But the end result is that I got the house and my boys live with me. My ex and I have joint custody, (mostly affects decisions on school and medical stuff) but I'm the residential parent. The boys spend Saturday night with their dad, and alternate Friday nights. In addition, he also gets them 3 1/2 weeks in the summer.
I get child suppport til the boys are finished with college, plus spousal support. For now, I'm able to stay at home and be a mom, although I've been taking classes, volunteering in my field and hope to find work eventually.
Regarding full custody, if my boys were younger, I would have put the extra effort into seeking it. The custodial parent gets to make the decisions for the children. But my boys are teenagers, so I was mostly wanted them to continue to live with me since they are old enough to have a say in decisions. I was told that if our divorce had gone to court that I probably would be awarded custody of my boys because I had been the one at home taking care of them as a SAHM. The other thing that turned out to be in my favor was that my ex moved out and the boys lived with me during the year we worked out the divorce. The judge wouldn't change the children's living situation unless that parent is unfit.
No one can say whether your friend will get full custody of her kids, but in my case, our parenting plan ended up pretty close to what I requested.