Welcome! First, they can easily be caught while they're roosting at night. Second, they'll get all the vitamins they need from a good chicken feed - I recommend an all flock with 20% protein. Third, I'd get a coop with an enclosed run to keep them contained. You can find ideas in the coop and run section of the forums. I would not advise getting a prefab coop as they're usually, too small, too expensive and have too little ventilation. You want at least 4 square feet of coop space per bird and at least 10 square feet of run space per bird plus 1 square foot of ventilation per bird. These numbers are a bare minimum. it's best to provide more space and ventilation. Since they can obviously fly, I'd cover the run too. Fourth, the only supplements they need are grit and oyster shell - both served on the side free choice. Fifth, you can gain their trust by sitting with them and occasionally tossing them bits of food. No need to force anything, it actually might be helpful to read a book or play on your phone while out there initially
If you have any more questions feel free to ask!