Are minds made of ideas?
No. The mind is a different thing from ideas. Ideas are dependent on minds, but minds are not dependent on ideas. Minds are substances, which exist independently of other things.
Do we have ideas of minds?
No. We have notions of minds. In Berkeley's ontology, there are two kinds of things, ideas and minds. In Berkeley's theory of knowledge, there are two kinds of things, ideas (ideas play a role in both metaphysics and epistemology), and notions (which are how we know and think about minds).
Can the mind act on ideas?
Yes. Minds act on ideas of imagination, and also on those ideas that we share with God. Remember that when we sense bodies, the ideas of those bodies that we perceive play a role both in our understanding of bodies, and also in the composition of the actual bodies. Similarly, we can act on ideas that we sense, and in this way influence the world.
Is the mind free?
Yes. The mind is free, because on Berkeley's view all causes are minds. Therefore there is no worry of a deterministic challenge. And since all causes are minds, talk of minds freely causing things is not any more obscure than any other causal talk.
So where does this leave us? Berkeley maintains that on his view, God is closer to us than ever before. Free will is easier to understand, the death of the soul is hard to understand and questions of the resurrection are clarified. It becomes slightly easier to be a theist, and metaphysics is simplified. Everything else remains the same. Berkeley thinks this is all to the good!