Old Indian vs Bogo or Nimzo

Nimzo is best

I like the Bogo Indian. It is more flexible. So perhaps the Nimzo you'd like better. I think there are more aggressive options with the Bogo while the Nimzo is more of a strategical battle for the center. I'I'm still figuring out the pawn breaks for both variations. Good luck.

Bogo-Nimzo-Indian with both Nc3 and Nf3!

There are transpositions between Rubinstein Nimzo-Indian and Panov-Botvinnik Attack.

This depends on which line of the Panov he plays.  If he plays 5...e6 and answers 6.Nf3 with 6...Bb4, then yes, absolutely, and the Nimzo-Indian should be automatic!

If he plays 5...Nc6, or the more suspect 5...g6, then there's no real correlation.

Nimzo + Bogo is very solid which will most likely suit you as a Caro-Kann player. Just try it in a few games. Hope this helps

Thanks for the responses. I'll try your suggestions out.