As @Marie13 mentioned, BPW is really just another back inflate BCD. Spend a little time in a pool getting it adjusted right, and some simple buoyancy and trim checks, and you're good to go.... No instructor necessary.If I take the OW class with rented equipment, pass, and want to keep diving, but hate the jacket BC (which is very likely), and buy my own long hose regs and BP/W, I will be left to my own devices to learn to use them safely. In other words, when/where/how could I then switch to my own gear under the supervision of said instructor?
As for long hose.... Since you are at initial OW training and any restrictions that make a true (7 foot) long hose necessary are far in the future, I would recommend what some call a "streamlined open water" arrangement. I do primary donate with a 48 inch hose that runs under my right arm to a 70 degree elbow on the second stage, with a necklaced alternate. No messing with the loop behind your neck of "true" long hose, but still gives more standoff than traditional recreational reg sets and keeps all the benefits of primary donate. Just practice OOA drills regularly with your dive buddy (like we all should anyway) and make sure any insta-buddies know you use primary donate.
Respectfully,
James