Used to feed our chicken all kinds of table scaps but egg laying was inconsistent. Local farmer gave me some advice to keep laying chickens on a well balanced layer-feed mix with all the necessary ingredients and my hens are very consistent now. Used to feel good recycling scraps to the...
2.5 yrs old isn't too old. I had some that were 6 years old that finally quit. Make sure you're giving them the 14 plus daylight hours with a light set up compensate the shorter days.
Have my light come on 4:30am so that they will get sufficient light. Shuts off at 8:00am. Cold has not affected their laying. In fact my 3 of my young hens have just started laying in the midst of the cold stretch here in the Northeast. 9 eggs today 12 hens.
Make sure you have an alternate light source. They need extra light during the winter moths. Our hens are laying without skipping a beat and it's pretty cold up here in the NE. All our chickens are young so that helps as well. Our older ones didn't do as well during the winter months.
Most likely rats. I'm constantly having to trap and poison them. Two or so years ago I set up a video camera in the coup. Was devasted when I saw 3 dozen rats havin a party after sundown. Now I take precautionary measures on a regular basis to keep the rat situation under control.