Premium is higher when there is or has been more expected movement. Ie before a news event or when markets have moved a lot.
Bid offer will vary by instrument. The more traders trading it and the more volume on it. (Similar but not the same) the narrower it will be. On any market: Forex, futures, stocks, options, binaries, and spreads. Remember, options vanilla or binaries or spreads, are all option derivatives and usually have a wider bid offer than the underlying.
