There are few hard and fast rules with Altec ID, they made many changes, and often. They were innovators, when they discovered an improvement, they took it to production ASAP.
Not even close in that condition, maybe 500 bucks if it has original good condition diaphragm, chances of that are very slim. Uninformed buyers will happily pay more.
Not really, to an informed buyer.
Smooth paint and smaller Altec font on the rear cover, early ones were a nice hammertone finish, and 288C doesn't require machining to put a modern diaphragm in it. It's truly field serviceable. A more desirable driver for people who are actually going to use them as intended. Early 288C probably had water slide decals, there were probably 3 types of decal for 288C
RWB's are usually a typewritten fine/thin paper label varnished in place like the original VOTT decals, there were 2 styles.
Should be any of a number of shades of gray, exact color changed often. Brown would be characteristic of components made for Northern Electric.
Will measure the same as a driver marked 16 ohms, the 24 vs 16 ohm thing has to do with the early convention by which they measured impedance.