I always think of Apostles as those who go out and spread the word of God by laying down a strong foundation of the gospel message and then appointing leadershp to carry on the work… the other four ministries. It is also the duty of the apostle to visit sites previously started and to evalutate whether they are still in the faith (basic foundation) and to bring education or correction to those whom he has appointed to oversee the churches the apostle helped establish. There is a also a time when he should meet with other apostles and elders to evaluate all the works currently being done in the name of christ to ensure the truth continues to be spoken in love. At least that is my view on who they are and their responsibilities.
As Roy has written, the person must be humble above all else… fisrt to God… then to others. I am reminded that Moses is, after a fashion, an example of what an apostle should be. It takes a very humble man to stand before God to get direction. It takes an even humbler man to meet out discipline, with love for God first, a people (Israel) a close second, followed by individuals.
Paul came right out when his authority was challenged… he said not by their speech but by the power that came from their words. Paul’s apostleship would be proven by the power… signs and wonders, done at his command. For where the word is preached there is power following. Of course where a people are sensitive to God then that perfect witness within will confirm or deny that an “apostle” is from God.
Take your pick… the eternal witness (for the mature) or the power of God displayed among you (for the young in faith and the lost).
One further thought. When I am in a situation where a minister or ministry brings a bit of confusion, then prayer is a must until the Spirit gives insight to what is actually happening. Normally, there is a witness from God that I need to see beyond what my eyes perceive… I then enter into prayer until I can see with my spirit what is going on and/or what the truth is. Prayer is the key.