I've also used the screw adapter with a pull chain in my last dark/bathroom. In my current dark bathroom, I've got one light socket in the ceiling and no electrical outlet, but the enlarger is actually in the hallway adjacent to the bathroom--much roomier and more comfortable, but it means I can only print at night. So in the bathroom, I put in a two-bulb light socket adapter with a pull-chain adapter on each socket. One side has a Verilux daylight incandescent bulb and the other side has a Kodak LED safelight. As a process timer, I use a battery powered Paterson triple timer.
To black out windows, you can order Delta plastic blackout material from B&H.
A handy thing I had in the previous dark bathroom was a typing table with wheels for my enlarger. The bathroom was tiny, but I wheel my Omega D-II on the table over the commode. To get the enlarger to sit on the table, I added an extra set of 4 rubber feet from a hardware store to the baseboard to match the footprint of the table.
Another handy thing I've found at Bed, Bath, and Beyond is an expanding metal rack used normally to increase shelf space in a place like a closet with a high ceiling. I can put it in the bathtub to elevate my trays or put two trays on top and one underneath for more space.