to slow down factory construction by capis, raise their taxes so that they are producing less per day in reserves. You can use the rich taxes like a speed control in that sense, lower if you want to give the capis a boost to build things, higher if you want to slow them down to a managable rate that keeps pace with your economy.
You can use the tariff slider this way as well, however it affects all POPs money, not just the rich, so if you set it too high your lower and middle POPs might not be able to fill their everyday and luxury needs, which if they can produces a constant -0.05 and -0.03 MIL per year respectively.
As for Italy, send a diplomatic option to form an alliance. Note though that even at +200, if you have been a warmonger and have significant badboy, you'll be about as popular as a leper, and may very well get refused in your courtship.
and to check badboy hit F12 which opens the console, type badboy and hit enter, and the score will pop up. Hit F12 again to close the console.