By the time they took the reigns, I assume that the Apostles all knew their scriptures inside and out. They were sent, and I can't imagine God sending the Apostles out empty handed. I think of:
Mark 13:11 : Whenever you are arrested and brought to trial, do not worry beforehand about what to say. Just say whatever is given you at the time, for it is not you speaking, but the Holy Spirit.
Luke 12:11-12 : 11 "When you are brought before synagogues, rulers and authorities, do not worry about how you will defend yourselves or what you will say, 12 for the Holy Spirit will teach you at that time what you should say."
So, just as you go on to say, they did have the Spirit to guide them. I think it's reasonable that this applied not only when they were in trouble, but also when they were preaching.
But lumping all the Apostles into the same knowledge class is a mistake I believe.
I don't think they all had equal knowledge, since they all continued to learn throughout life. However, I think it only makes sense that all of them were completely qualified by God to preach all of His word that God wanted preached. (At a minimum, I would think this would include a solid understanding of the OT.) God chose them, sent them, and gave them this specific task. He wouldn't leave 'em hanging. :)
You mean the way he does "US".. I have Gods anointing much in my life and been on my own in between.. Well I wasnt on my own it just seemed that way.. Otherwise how could I learn ANYTHING.. Even Moses made mistakes.. so have I.. What about Jacob... Jona.. and Saul(paul).. Peter(Cephas) is biggest doofus of all..
Yeah God(Holy Spirit) can leave us hanging.. a prayer away from disaster.. "Some" wouldn't pray otherwise.. Know what I mean..