Our mediation was very amicable
My mediation/divorce was very high conflict. I am quoting because of the contrast in attitude by the people getting divorced (i.e, my divorce versus OIN's divorce) but not in the importance/effectiveness. If I had a regret about my divorce, it's that I did not push for MORE mediation (we had three sessions at three different stages of my divorce).
If people are reasonable, mediation is great because you have an independent third party saying what is reasonable/fair/legal. It's shocking how many people have highly skewed versions of what is legal and fair. And I don't necessarily mean that it is negative way... I watched my (now) wife's mediation with her ex and he had a bunch of ideas on how their divorce should proceed that were complete nonsense... but he was actually calm/rationale and basically responded with "Oh, I didn't know that" and things progressed pretty quickly after he was educated.
If people are not reasonable, then mediation is great because you have an independent third party saying what is reasonable/fair/legal and this person can somewhat serve as a proxy for a judge.
In my first session of mediation (with lawyers present), we actually reached a bunch of compromises that were very reasonable. Unfortunately, we did not sign anything and after the fact... my ex played games after the fact and she had a very skewed version of our previous verbal agreements. In my second session of mediation (prior to my appeal), both sides basically said "we would prefer to see what a judge says rather than accept their offer" and that was fine. In the third session of mediation (after the appeal), both sides said "we would prefer to see what a judge says rather than accept their offer" for about 90 minutes... at which point, they decided to reduce their settlement offer by more than 90% and we reached a settlement (i.e., they were clearly bluffing).
My recommendation is to go into mediation assuming that it will be a productive session. If your primary issues are the house and maintenance... then do your homework and come prepared for both of those issues.
For the home value, I would look on the internet and find comparable properties (sold price is better than asking price) and try to produce an estimate for your home's value. I would recommend that you try to be fair to him and to yourself on this price. For example, I estimated our home's value (fake numbers) at $125,000 and my ex valued it at $85,000 and "not a penny more!" My value was based on comparable prices and her opinion was simply her opinion. So, we agreed to get an appraisal... and the property appraised at $140,000 (my point here is I was being generous to reach a quick settlement -- don't do that!). If the two of you cannot agree on a value, then just ask for an appraisal and be done with it. An appraisal is probably going to cost you about 2 hours of lawyer/mediator-time, so there's not much value in arguing over a price with an attorney and/or mediator present. Just pay for an appraisal and be done with it. (How you split equity in a home is a more complicated question because that's not liquid cash, right?)
Maintenance is much more complicated and it likely varies based on where you live (i.e., laws vary by location). In my location, it's based on income and the standard of living established during the divorce. A lot of people try to dicker with their income and here it helps to know the laws. Does overtime pay count? (in my location, no). What if someone doesn't work or only works part-time? (in my location, everyone is expected to be able to work full-time... or devote themselves to education so that they can begin working full-time). What about side-hustle income? (doesn't count where I live). I would definitely bring the most recent 3-4 years of W2's and/or tax returns.
You should also come up with a budget that makes sense for yourself and come prepared to suggest changes to his. Here again, people will dicker. My ex literally tried to convince the judge/mediatior that her personal budget required more income than what we experienced when we were together... virtually ever cost was inflated substantially. For example, she claimed a $150 per month water bill; lucky for me, I paid our bills and it was $150... every quarter, not every month. Come with fair estimates for yourself and be prepared to challenge his.
You seem to be reasonable and primarily interested in getting a quick settlement rather than a fair settlement. Let me caution you against that. Think about what is LEGITIMATELY fair for you. Also, do not trust your ex to be honest. This will sound ridiculous, but during my last session of mediation... my ex claimed that *my* salary was $10,000 per year higher than what it actually was. I had provided her a copy of my W2 and she spent 10 minutes trying to convince the mediator that I was lying about my income... which was quickly resolved by showing the mediator my W2.
I strongly urge you to not sign any agreement without your attorney reviewing it. Yes, the mediator should be fair but the mediator's job is to reach an agreement. Your attorney's job is to protect your interests. There is a difference in what they are trying to do that is very relevant for you.