One thing I picked up through (repetition) was to make sure I had things covered from most angles and that way I was sure that what I was saying was correct. To be honest I found there was more often than not another way at looking at things.
Whether that be a painful reality check or I had stumbled across it and realised it myself happily.
How they calculate the finances will be one thing, I got help with that, but I opted out of legal help for the bulk of it and got other support services, that showed me how to calculate it myself. In the end, I got a result I was happy with. I ended up understanding things and the legal fees stayed in my pocket.
Don't know about the house, I think it would just go down in the split of your assets. There's the cost to you for rent and the loss.
I learned big time about mediation the hard way that I had to prepare for it and I did act like an idiot in our first one. I ended up trying an online mediation for our second one. It was cheaper and easier to get happening. I was more prepared and learned I had to listen to my ex. I would always say that if you want to be heard you need to listen first.