"Is there a way to batch convert point text layers to paragraph text layers and give them all the same bounding box?"
Not sure about batch converting them, but you can make a blank paragraph text layer at the size you want and pick-whip it's source to the existing layer. Then it will create line breaks where there are spaces. I think Phil's expression could break lines in the middle of words?
This could be tedious to set up, so you could duplicate your blank paragraph text layer and have it look at, say, the layer above it for it's source text so you wouldn't have to pick-whip it every time with an expression like this:
thisComp.layer(pullFrom).text.sourceText
... where you apply that expression to the Source Text value for your blank paragraph text layer and place the paragraph layer below the existing text layer in the stack. Then it's just a matter of duplicating that layer.
Dunno. Maybe that helps?
- Nathan