I should clarify that this will be a flip, and I would be DIY'ing the wall (I'm formerly a carpenter and this particular wall would be an easy one with regard to the great points you brought up).

The huge repair was definitely a red flag that made us worried for the rest of the house, but after the inspection we brought in a few other experts (structural engineer, masonry contractor) who gave us some encouraging assessments.We ended up getting another $5k off and are going to move forward.

Sean, the issue you could run into is if a lawsuit is brought to you naming the LLC. 

We brought in a partner and basically syndicated it like you would with an apartment (it was actually a TIC, but that's a long story), which is probably the best way to do the deal.

I've had issues with lenders assuming that I know all their secret little rules lol like on my last deal, I brought a third loan to my lender (I purchase long term rental BRRRR condos here on Maui) and he said "oh sorry, we don't give more than 2 loans in a given condo building".

Have any of you done a partnership where you've done all the work and someone else has brought all the cash for a somewhat turnkey buy and hold?   

You do not want to get tangled up in a discrimination suit because you turned down George who brought a dog into the unit and produced a certificate from some online sight that says the Saint Bernard he has in the apartment makes him feels secure during rainstorms and full moons and this keeps him from having nervous seizures.

I brought this to the attention of my lender, as I could have sworn that I had shared my plan to rent out rooms from the very beginning!

I assume the value is that you brought the deal, but even that is not worth 50% of the profit.

I would think a remodel will happen and be completed long before an ADU is completed unless you have a small manufactured home brought in.