If you want to determine which way floor joists are running, you can get a pretty good indication by taking off a cold air return cover and spotting the joists from there. (the direction can change around stairways, though)
Determining wood floors, bearing walls, joist direction, ect . is extremely important and should not be left to "best guess"
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Find or make a "friend" that can visit your place on site and do some poking around.
Getting a look at the existing drawings is best and having the landlords' permission is a necessity....IMO.
Mitch