I have a room for the rabbits attached to my utility- it was purpose built for them. It's brick built lower half and timber built upper with felt apex roof and the door from my utility opens into the rabbit room.
I have small catflap sized little doors that lead from the rabbit room into their runs. The runs are tall enough for me to stand up in and are meshed with fox-proof wire a slabbed floor and a corrugated plastic roof. The mesh panel doors open in to the garden.
after nearly 20years of rabbit keeping and sliding onto my bum in the mud and rain,

going out with a torch in the cold winter nights to cover hutches with duvets etc I think I have now found the perfect set-up for me and the bunnies too.
In the daytime they have the run of the garden as they love to binky and graze and dig and mooch about the bushes, but if it rains they can go back into the shelter of the run. If I need to pop out I can lock the run-to-garden panel doors and they are safe and dry with space to move...they also have access to indoors through the little run-to-rabbit room catflap size doors. At night they must come into the rabbit room and I lock the little doors. They still have plenty of space with litter trays food water and a hutch they like to jump in and out of. They are never shut in the hutch. They sleep on a blanket in front of the hutch.
In the bitter winter weather we have heaters that we can plug in on top of the hutches out of reach and snugglesafes.
It means I can go in and out to see them in the evening whenever I want-with both them and me, nice and dry.
As the bunnnies you have taken in are half wild I would think outdoors grazing in the day is best for them. Wild bunnies can jump VERY high when mature- those 3ft dog pens are a doddle for them to jump over! so make sure you have good perimeter secure fences-( I saw a wildie baby we once fostered clear our 4ft (internal)mesh fence with ease

and they are very good climbers too)
I would suggest a good quality secure shed (or unheated room) for night-time that is as close to the house as possible for easy access to the bunnies in the winter evenings, and greater winter warmth at night and greater protection from predators.. If they are kept in a cooler unheated room they will still develop their winter coats which is essential if they spend lots of time in the day outdoors grazing.
If they stay indoors with you then you will not be able to let them out to graze in the cooler months - only in the summer. Indoor bunnies must have the house "bunny-proofed so they don't eat wires- plus it depends how you feel about hay getting everywhere in the house and litter trays being around. Bunnies are fairly easily litter-trained but they do miss sometimes!

If you like to play loud music then their sensitive ears wouldn't like that.
Some bunnies seem to enjoy being indoors and others hate it- you will have to decide what's best for them and you.
sue
