Hello, I am going to replace a bathroom floor that has engineered wood flooring with tile. The flooring runs out through the door to other side of the connected hallway. The door jams are tight on the flooring. I have an undercut saw to free up some room for the marble threshold. I have 2 questions. First of all, what saw would be best to cut across the flooring in the doorway without tearing it to pieces. Secondly, what tool/saw would be best to cut the engineered flooring that is under the door jam. It will be tight and I will need a good straight line.

I have 200 year old pine floors. The planks are 16' long (length of rooms) 3/4" thick and between 12 and 22 inches in width. They have been nailed down with cutnails. Now there are two issues with re-finishing these floors. One there are gaps between the boards ranging between 1/8" and 1/2" this isnt really a problem because I plan to fill the gap with manilla rope stained to match the wood aftrer the refinishing is done, but the problem is that the floor is cuped and crowned significantly. Its not awkward to walk over or anything but if you took a 3' level and laid it across the planks you would be able to find gaps under it as big as 3/4" in places. This clearly makes attaining flattness with 3/4" planks impossible. Now I already sanded a good amount of paint off these floors with a rental 8" drum sander by going across the grain so that it would follow the ups and downs of the floor, but I havnt done anything else in months to the floor, other projects have been ongoing. Sheetrock, paint, etc. Anyway my wife is talking more and more of hiringing somone to come in and refinish the foors. Is there any chance that a floor refinisher will have any way of dealing with floors so out of flat as mine? Im asuming he will just charge a ton and do the whole thing with a 6" disk sander or somthing. Can I tell her Ill do the edges, the low spots that still have paint in them, and remove the scratches myself with my palm sander or should I just let her hire a pro? Thoughts? Thanks.