confusing behavior...laid three eggs then stopped

I have one RIR hen and one light brahman hen. Both are about 22 weeks old. I was given three young bantams of unknown breed two weeks ago who started sleeping in the nesting boxes (that no one was yet using for egg laying). So, I blocked off the nesting box to keep the bantams from sleeping in there.

Three days ago while cleaning the coop I found three medium-sized brown eggs on the floor of the coop under the nesting boxes. We took them out and put one in each of the nesting boxes to show hens where the eggs should be laid. I unblocked the nesting boxes and raked up the floor of the coop to disturb the area where the eggs had been laid. Normally they free-range all day long but today they are inside to be sure eggs aren't being laid out in the yard. The coop is big enough that I can continue to do this another day if need be.

But, there have been no new eggs since the first were found. So, here are my questions.
1. Is it normal for newly-laying hens to lay a few eggs and then skip some days?
2. Any suggestions for what I can do to encourage the hens to resume laying?
3. Will hens re-learn where to lay their eggs?

The nesting boxes are about 15" high x 17" deep x 17" wide. They have straw in them, plus now the "bait" eggs that were found on the floor.

And, last question--will the color of the RIR eggs differ much from that of the LB? All three eggs that were found are the same shade of medium brown and definitely too big for the bantams to have laid.

Thanks, in advance, for any advice!