Is there a direct bus from Liuting Airport to Jinan? If so, what is the frequency and cost.

I'm afraid there is no direct bus between. I suggest you take shuttle bus line 2 (bus no. 702) to the local Railway Station, where there are frequent bullet trains to Jinan. About the train schedule and cost, the website can tell you:
https://www.travelchinaguide.com/china-trains/