Re: Grease fitting?
older coaster brake hubs had an "oiler hole" and they work quite well. they're different than zerc fittings like cars use, as they were basicaly just a little capped off pipe in the hub. hubs like "new departure" and "komet" hubs had them, as well as many others.
they were mostly used for keeping the coaster brake shoes and worm gear lubed. it didn't help much for the main bearings, mostly because the grease would have to fill the entire hub before it'd squish out to the bearings, or it would have to break down enough to flow into them.
as for the bottom bracket and the headset, the same would apply. if you tapped a fitting into the frame, you'd have to pump the tubes so full of grease it would just be a big mess. then the grease in the bearings would break down, you'd pump it full again to push the old grease out, and it just sounds like a hassle.
it's easy enough to disassemble the headset, BB and hubs, and with repetition, you can learn to do it pretty quick.
i can overhaul a complete bike in 2-3 hours, and another bonus is, you can inspect all the parts as you clean them.