How many floors up do you live? May sound like a really silly question but you would need to 'puppy proof' any kind of balcony to prevent accidents. I'm not a firm believer of dogs living in flats, but I know people do it. You would also need to check with your landlord or local authority to see if your tennancy allows a dog to be kept in your property as I know some landlords or local authorities do not, I would read through your tennancy agreement (This is if you don't own your flat btw)
Being as you have no garden area as such, your dog would need to be walked three - four times a day depending on breed and the age of the dog, but almost certainly would need to be walked as soon as you got up to relieve itself.

Bitches are usually spayed three months after their first season, some vets will do it before, some will not it's just a matter of ringing around to see who would be prepared to do it. Bitches usually have their first season from six months old onwards, again depending on the breed, it really can be a waiting game.

Hope this helps