Over-run with chickens, hey?
I think you probably need to look at this issue over a period of a few weeks. Why? Because as you've just hatched out chicks (and apparently have more coming), a good percentage of those will be cockerels - which I presume you won't want to keep.
If that's the case, you probably need to allow time to determine who is a boy and who is a girl, and I suspect you will be able to reduce your flock size fairly considerably once you know that for sure. The excess roos can either be sold or culled. The recommended ratio for roosters is 1 rooster for every 10 hens.
As far as your mature hens go, you will need to spend some time and figure out who is laying and who isn't. I have one old girl who I adopted 6 months ago and she has never laid for me. She was worth keeping though, as she acted as a buffer between my existing flock and my new chicks - protecting them, teaching them and introducing them safely into the flock. She was well worth keeping for that reason.
If you have many non-producing hens, you have a decision to make - based on who is not laying (and taking into full consideration the season and daylight hours available, the moult, and those recovering from brooding chicks) you can sell or cull out the non-producers.
Going forward, you probably need to consider your stance on allowing broody hens to sit on eggs. If you don't have the room for any more chickens, it might be a better idea to use a buster cage and break any future broodys. If that does not appeal, alternatively, you may be able to sell any surplus stock you accrue.
Krista
ETA: I tend to ignore the physical age of my hens, as it will vary between breeds as to what 'old' is anyway. If they are still producing eggs regularly, that's a cue to keep them. If not, they can go. I don't base that decision on their age at all.
