[Azaghal]

Soloing is not recommended for beginners. But after you played through SOA a couple of times and found out all about NPC interactions, races' and classes' advantages and disadvantages, know all quests by heart, you start looking for a new challenge: Soloing.
Your character may become pretty powerful rising through the levels quickly with all the exp for him alone. You must choose your equipment carefully, find out about the best suitable combinations of gear and weaponry. Tactics in battles are no longer choices of how quick or with how little casualties to win, but a question of sheer survival.
Well, concerning your other questions I suggest you try a solo game to find out by yourself. It is possible. Maybe start with a versatile and strong class for the beginning, otherwise it can be frustrating. Choose a paladin, ranger or fighter class character (to dual over later).
Enjoy!