Not sure if this can be modded...
1) Hen house. Is it possible to mod a fixed-size pasture (like a building) allowing only chicken (just a regular chicken, not a special kind) as an animal and consuming grain to produce eggs and chicken meat like a regular pasture would? The goal is to squeeze considerably more animals per building's footprint area at the cost of consumed material (grain).
2) Taming wild deer. Again, "is it possible" to make a product switch in the Hunting Cabin (Hunt deer/Tame deer) to regulate behavior of hunters - either kill a deer or convert it to the livestock animal once encountered?
1) i think a special chicken pasture as chicken coup can be made. however, if it functions as a pasture, it will only allow 'work' as input, not items like grain etc.
2) not possible with current modkit / inner game workings. However, there is a deer as livestock mod available.