In the pit, the stop order is held in your broker's order deck (or handheld) with all the other orders, which are arranged by price. It isn't shown to the pit at all until activated by trading through the stop price. As for knowing whether it's a stop, it isn't indicated to the pit as to type. Once activated, it will just either be shown as a buy or sell. As for picking your stop, the pit might try and run a price where there are likely to be a bunch of stops (e.g. just over the previous day's high or just below the previous low), but the idea that anyone is trying to pick off an individual small stop order is just fantasy, there isn't time, motivation or risk/reward to push prices to do it. If you place your stops where a lot of others do, however, they will probably get picked off from time to time.
Good trading,
Jessie