I also have a F.I. forced air incubator. As far as the humidity is concerned, I think it really has to do with your altitude, if you're not at 1000+ feet above sea leave (i think) then most people use the dry incubating method, when you're at higher altitudes, you use higher humidity settings. With the dry incubating, you don't add water at all until the humidity drops below 25% for the first 18 days, then you raise it between 55 - 60% (the exact number varies per my readings). These are the settings I use as well and I actually just hatched some chicks this morning, and have more eggs that have staggered incubating dates. I use my FI incubator as my lockdown bator. Usually with mine, when I don't add water my humidity stays between 40% and 48% and I then raise it to between 55 and 58% for lockdown (I add about a tablespoon of water when it drops to 50%). Again, the humidity is based on where you live, I live in the Virgin Islands, so I've had add holes in my FI incubator in order to drop the humidity below 48% for days 1-18, and then tape them back closed and plugs out for lockdown to keep the humidity below 60%. Also I keep the red vent plugs out the entire time of incubation.
This is just the basics, there's always some tweaks that can be made due to where you are in order to get things right for you.
Hope this tidbit of info was somewhat helpful.
