I need to remove a 45 yo cast iron tub for a remodeling job and don't want to damage the surrounding walls etc too much. How were these things attached? And how do I unhook the plumbing etc to remove it? Thanks!
Pick one of those two, or realize that "too much" has to have quite a high threshold in this case. They don't come out easily, and they were put in before tile, etc was put on, and the plumbing you need to disconnect may not have been provided with any access other than "bash the wall open when you need to get at it." If you are not comfortable with seeing the walls of the alcove ripped back to studs, you may not be ready to remove the tub. You can't really properly replace it without going there, anyway.
A three sided alcove tub has a lip that goes under the tile. It is supported by framing and sometimes by a lipped nail (Just an edge hangs over).
Take care breaking it, it will shatter very sharp shards, so eye protection with side shields is necessary.
It can be cut with angle grinder with metal blade (that method will require dust mask.
Unhooking the drain is similar to a sink drain: remove the trap. If you cut the tub in half, just leave the overflow attached.
Even in half, cast iron is heavy. I contact metal scrappers who will haul it out for free. A Kohler 5ft x 18" was close to 400 pounds