Health issues can include Heart problems, Spinal problems, in Giant Lops- Ear problems, Entropion/Ectropion.
IME bonding a Giant Rabbit with a smaller Rabbit is possible, it really depends on the individual Rabbit's character as much as their differences in size.
Giants can be housed indoors or outdoors. IMO if indoors they should be as 'free range' as possible and if housed outdoors then a large shed with a permanent large run attached or a large dog kennel/run would be essential. I dont think any Giant breed should live in a hutch.
A few of the Giant Breeds whom I have cared for:
The late Geoffrey, a Continental Giant, who was severely brain damaged due to an adverse reaction to a GA
The late Victoria Meldrew, French Lop, a Doe traumatised by spending 4 years in a 4 foot hutch. She was VERY aggressive as her feet were a mass of abscesses. But eventually she become a gentle giant
The late Big Libby, a Flemish Giant, rescued from a BYB at 10 weeks of age with a huge abscess on her spine
The late Colonel Colin, a Velveteen Lop (English Lop x Rex)