Paddle shifters can simply be engaged by clicking them. If you're in D, however, the car will go back to auto in few seconds. But if you're in S and engage the paddle shifters then it will remain in 'manual' mode until you take the car out of S.
And yes, if you satisfy yourself thoroughly as to the condition, then a 2016-17 Turbo will be a good buy, though ideally you will have to mix HOBC or use full HOBC.