About the turn signal -- no, stalk-mounted signals are not considered part of the fairing. A bike's fairing might have the turn signals molded in as part and parcel of the fairing -- in which case the rule would allow them. But stalk-mounted -- could break off in case of an upset.
You've got answers to your other questions, but I'll add that if you've got a clip on the rear axle nut (vs. a true cotter pin) it's good to wire that pin to the swingarm (or something back there) -- not that the clip will come out, but if it's wired -- it'll be easy to find once you remove it. Go ahead, ask me how I learned to do this.
Back to your question (even though this one's been answered) -- for class display you'll want to have it in letters at least an inch high (like so many things, bigger is better, within reason), on both sides (commonly on the tail section), readable from the side (not the top), and in colors that contrast with the fairing. At Maxton, commonly the class is displayed (for example) M/PS/G 1650 - 4. That'd be information about the bike and bodywork first, the fuel of the class in which you're running, the displacement class you're in, followed by either a 2 or 4 or R to designate two-stroke or four-stroke or rotary.
The bike's registration number should be in numbers at least 6-8 inches tall, if possible, and commonly they're displayed on the front of the bike (but most anyplace is okay as long as they're readable when the rider is on-board), and, of course, in a color that's contrasting to the bodywork. If your bike doesn't have bodywork you'll be allowed to display this information on a number plate -- which must be of a certain size. See the rulebook or ask for details if such is your case. Once you're through inspection you'll take the completed form to registration and they'll give you (among other things) an "inspected" sticker to put on the bike. Those are best displayed on the (rider's) right side of the front of the bike.
Finally: PLEASE fill out the log book before you get to registration. Not while you're there -- you'll slow down the inspectors if you don't have it done, and we can't inspect your vehicle 'til you've filled out the logbook. You'll see this on the inspection sheet -- at the top of the list -- "Is the logbook filled out and the numbers displayed properly? As JD said in the SCTA thread -- please do it first. Otherwise we reserve the right to toss your butt out of line, make you go fill out the logbook, then wait in line all over again before getting inspected.
Thanks, and we look forward to seeing you soon. We leave home two weeks from day-after-tomorrow for our 1,400-mile trip to Maxton. Whoo-hoo, it's coming soon.