Yes I think you should be good for the 12th 13th for lockdown.
With eggs that dont make it I just wrap up and put in the bin. A lot of folks open the egg and see what wrong with incubation and why the chick didn't hatch.
With too many Roos you can either try to rehome them, grow them on and put them in the pot or cull as soon as you know they are boys. They can live happily also in a batchelor group of just boys. If you have more than one roo in your flock they can fight over the girls. Might not but they can.
I hatch mainly polish so they are not very meaty but I give them a chance to find new homes. If no one takes them they are culled.
Here is an article on introducing new birds ~
https://www.backyardchickens.com/a/introducing-new-chickens-using-the-see-but-don-t-touch-method
This is how I've done it in the past and it worked well for me.