New to hatching & breeding. Please help!!!

We currently have 11 birds.
1 RIR rooster
5 RIR hen
2 barred rock
3 Easter eggers

Only 1 maybe 2 RIR are laying. All the Easter eggers lay. I don't think any of the barred rock are laying. I understand everyone says lack of daylight but this has been going on for 2-3 months since we got them at least.

So my question is this. I'm thinking of getting rid of 2-3 RIR. Replacing them with 20 week old red and black sex links. Can I then breed the black or red sex link with my RIR rooster? Will I get a hybrid bird in return or another RIR?

Also does my coop look to small for 12 total birds. It is a 5x8. The coop run is large enough for 50+ birds with separate feed/water

How hard will this be to integrate? Am I asking for trouble