Your First Question: Is it too late to top?
Yes, it really is. It will stunt your plant. You should give at least a week of good veg time (in soil) after topping before flowering. You should do no major pruning during flowering.
Your Second Question: Can I take a plant from a flowering plant?
You can take a clone from a flowering plant, but it will not respond as quickly.
Good Luck - JJB