Here's an interesting article to get you started:
http://www.themodernhomestead.us/article/Broody-Hens-1.html
There really isn't a dependable way to make them go broody. Broodiness is a hormone change. There's someone on here who says he does it by confining the hen to a dark cage, I forget for how long, at least a few days; I wouldn't try that myself.
The article mentions Orps as being inclined to go broody, but none of my 3 ever have. Kraienkoppe is a very broody breed, I had 3, all were not only broody but wonderful mothers. I've never had a broody EE and never owned a Polish. Silkies and OEGB are famous for going broody. My BA 's also tend to go broody.
For feeding just the mama and babies, mama is not laying while setting or raising chicks so I just feed them all starter. My chicks tend to get themselves into the regular flock pretty quickly so I make sure they layer is too high for them to reach, as high as I dare for the hens. I don't care whether the hens eat some of the chick feed. Some people say not to let layers eat medicated chick starter. But I eat my eggs no matter what I give the chickens. That's not the recommended way, but then I'm not alone, either.
Your feed store/local chick supplier probably orders from Ideal as they are in Texas and the nearest large hatchery. Mine will order certain breeds on request and call you when the chicks are in, though they also sell to walk-ins so you can miss out on a breed if you aren't timely. Ideal carries Kraienkoppe (they are very pretty, look much like a brown Leghorn.)
You can probably put chicks under a good broody once she's been broody for just a few days; you certainly don't have to wait 21 days. I've done it but not early; I'd try it any time after 3 or 4 days of broodiness.
If I were you, unless you get lucky and one of yours goes broody (you never know,) I'd buy a few chicks in the spring of broody breeds -- I'm partial to Kraienkoppes but then I don't care for Silkies) and go ahead and raise them in a brooder one more time.
I like using broodies, too, just had one hatch 5 chicks over the weekend, and haven't bought chicks since the first round (this time) a few years ago.
Sorry about your predator losses. Me, too.