I'll get back to you on the gross weight bit but yeah, there's a little dot that gets stuck to the inside of the windscreen and the idea is you come in straight and level at a constant airspeed and when that dot is seen to align with the near edge of the deck you're landing on, you start the approach down.
Our aircraft haven't had that dot for quite some time now, I guess they just fell off and no one ever bothered replacing them, which doesn't really bother me because I always thought that method would result in the approach being much too steep.
I prefer what Supp. 8 says to start the steep approach and that is using the pitot tube as a reference. If you have a chance, take a look at both Supp. 8 & 9 and compare them. Makes for some interesting reading in my opinion.