The room I want to convert to a kitchen shares a wall with the bathroom sink so there’s plumbing right where it’s needed. 

Not sure if its plumbed. 

THE JOB:  relocate toilet, tub/shower and vanity which requires moving plumbing, electric and a heating vent. 

I'd have serious concerns for electrical, plumbing, HVAC, and the age of the windows, roof, etc.

So it would mean that any income/cashflow attributable to the 401k's ownership CANNOT go to you (or an entity owned by you, or one of the enumerated related parties or an entity owned by them) - e.g. acquisition fee, management fee, plumbing expenses if you do plumbing work, etc., but must go to an arm's length third party or stay within the confines of the 401k.I would not recommend it.But, it might also not be allowed anyway.

Another they turned off the thermostat and failed to turn it back on, resulting in frozen plumbing.

Others put crap down the drains or disposals that lead to plumbing issues.

At 100 years old who knows which have 5 years old electrical and plumbing and which are lead and knob/tube. 

We learned after the purchase that the house had plumbing and electrical issues.

Some mistakes we made: We learned after the purchase that the house had plumbing and electrical issues.