I saw from the other thread that your Rooster is a Game. He's pretty! I am also seeing from this post that your flock has really diminished over the years, although you have had chickens for a long time. You may not know it, but you have a good start toward rebuilding your flock.
What you will want to do is two things:
1. Improve the security around the chicken house so that predators can't get in. This might mean an automatic door closer or you going out and locking them up every night. It might mean some hardware cloth if there are holes. It sounds like it was just an issue of the open door, though, which is simple to fix.
2. Get some Game hens for your rooster. Game hens are very broody and will likely take care of chicks all on their own, while your Rooster has broody genes to pass on. Yes, your first hatches will be Games if you do that. Hopefully, there will be more females than males in your situation, because you are trying to grow your flock rather than raise exhibition fowl. In the situation with male chicks, you might be able to sell them. (An alternative is Bantam Cochin pullets - they are also really broody).
3. Now, there's a quandary. You probably want a dual-purpose flock rather than a bunch of Games. Games are pretty small and if they produce male chicks, the cockerels require individual housing so they won't fight. What you can do to diminish this problem is buy hatching eggs of the breed that you really would prefer, and put them under those Game hens at night once they have been broody for a day or two. The Game hens are light (they won't break eggs) and they can pretty much hatch anything you want in small clutches. I've had a Game hen hatch out 7 mixed-breed chicks.
The bottom line is that you would be using the Game hens (Bantam Cochins as an alternative) in lieu of an incubator to raise hatching eggs of whatever breed you actually want.