So, if they want to give you some of the land, fine. They can legally subdivide their land and give you a piece. You then build your house. The only question is if you want to live there -- presuming you can afford to build a house. This is a side issue, but the land can't be legally subdivided. We can only build because their existing house is so small it can be considered an "accessory apartment", even if it remains a free standing structure. And yes, we can afford to build. We're very close to paying off our existing mortgage on our current house. If they want to stay in the existing house, they can hire the repairs made. They don't seem to care if it's 'remodeled'; they just want to be safe. Well here's the thing. Their current house is just a mess. I don't mean dated, I mean that there's tile falling down in the bathroom (shower/tub is unusable), the roof needs to be replaced, wall board is popping out from moisture in the finished basement, the outside shingles need to be replaced, and too many items great and small to be listed. We live very close by. I've offered to set them up with contractors when we've had work done to our house, I've offered to help them with practical legwork involved in hiring contractors, if there was a hint of financial issues, I'd happily jump in and offer financial assistance. They want the magic person who will read their minds and do it all for free falling into their laps. Now a side of me says, "Forget about it!" and let them let their roof fall in if that's what they really want, but they ARE my parents and I do feel some diffidence about that stance. Exploring the ins and outs of us building seems to be a good time to also explore this issue. I think what we are going to do is talk to a few good builders and get some honest assessments about what is and isn't feasible. I'm thinking (hoping) some estimates about what's involved will either get them on board or allow us to figure we're not living there in their lifetime and move on.

Your main panel has 2 separate bars that attach to separate 120V feeds. By attaching a single breaker to one of these bars, referred to as "buses", you get 120V. To get 240V, you need a double breaker that attaches to both bars at the same time. When you install this double breaker, it needs to fit so that the plastic separator tab along either of the hot buses slips down the middle of this double breaker. Is this device a welder or compressor? If so, you only need 2 conductor cable to connect to the double breakers. If this device is a stove, then it may need 120/240V, in which case you need 3 conductor cable. The black and red wires will connect to either half of the double breaker, and the white wire to the neutral bus of the panel. That's where all the white wires and some of the bare copper wires may connect to. If the device is 240V only, you won't have a neutral wire. The black and white will only go to the breaker. The bare ground wire goes to the ground lug, where all the other bare copper wires attach to. You will need 6/3 or 6/2 cable to handle 50A. Since 6/2 is rare, you may need to use 6/3 and ignore the white wire if the device is 240V only. Mull this over and then ask more questions.

Get your financials sorted out first. It will cost far more than you think it will. http://www.remodeling.hw.net/cost-vs-value/2015/ Then, you'll need a plan to present to your city for permits. You can get that from a drafter, architect, or a design /build firm. The first 2 choices allow for cometitive bidding of the project itself, and the third chouce is less hassle to you, but probably slightly more expensive because of the lack of competition.

I addition to the yuck factor of not having a sink in the same room as the toilet, where would you store things like extra toilet paper, feminine hygiene products, and magazines? And you would want an exhaust fan in the toilet compartment as well as near the shower.