A lot will depend on where you get them from...large ranch, LF ranch or smaller breeding pen operation. Also the cover inside the pen and the traffic around the pen will greatly effect what you can do. I have seen smaller breeding pens with them do fine. I have also seen the exotics so wild they are hard to find in very large pastures.
This is very true. Also what animal you plan to raise in a pen must have considerable value when sold. Raising in a pen means that 100% of what they eat is fed by you at considerable cost and time. And like Ranchman said if it is going to be pen raised it best be semi tame. Other wise it will either kill itself or get out.