We will arrive on ferry from Ko yao Noi to Thalen pier and need to get somehow to the bus station to catch a bus to Trang.

Not having ever been to Krabi, what's the best way to get from the pier to bus station?

There is not yet a regular transportation from Tha Lane in Ao Luek to Krabi bus station, as this is not a (yet) a tourist trail. Most people using the connection from Koh Yao Noi to Tha Lane are locals living in Ao Luek, but working on the island. You best order a taxi in advance waiting for you on arrival.