Don't be confused by the two designations Lexus uses for the upscale sport versions of the RC. The F Sport is the tamer 3.5 liter 306 hp one. The F is the even more upscale screamer V8 that has 400+ horses and the price to match....about $30k more.
Really nothing you need to know before purchasing if you have already done your research. But, take your trade in to CarMax first and get their price. It will help in negotiating the value at the new car dealer.