Some of the more advanced incubators actually have a cooling option of 1-2 hours daily. After the first week, a cooling period has been shown to increase the hatch by a bit. There is a study on one of the numerous BYC incubation pages which shows it can increase your hatch by 1-2 chicks. Some of the much more learned folks on this thread probably know where to find the study.
I don't stress about letting the eggs cool when candling. I do stress about moving them around too much before day 7 though. Candling in the incubator works best for clumsy me!
Sweetheart, been there done that too! Started hatching yrs. ago..got hooked, had to try this that and another thing. I can't keep them all. I have sold many to try another breed here and there. I've decided I love my egg layers. Have to have a pretty egg in there..so I go for the blues or the Olive Green..getting a real pretty OE right now. I am a for real back yard chicken keeper..that's why I can't have all of the breeds I want. I love love the silkies. The winter gets harsh here, so, I hatch them at this time, have them for the spring and summer out there, then sell them. Yes,makes me sad. I just don't want to go through with what happened yrs. ago when I tried keeping Seramas through the winter. We won't talk about that. :/ I also love the Bantam Cochin. Do the same, have them for a while along with the layers in the spring and summer. I am usually over my limit in the summer, I let them free range when it's warm. I can't help myself..I love the little bantams! But want those eggs! Right now I do have one girl on the smaller side. She did well through last winter, so kept her. I call her Uggums because she was soooooo ugly while she was growing up. She's kinda cute now. Maybe it's because I love her. 
She is a smooth..SG. Anyway, have hatched ducks..no geese. Not enough room for them. I just wanted to try hatching them, also hatched some Button Quail...so Cute! Here is a photo of my Uggums. She's gone broody twice now, and has been a great mom. 
