Riga -Tallinn- Helsinki

Hi!! Would like some advice..I want to do travel from Riga to Tallinn and take the ferry over to Helsinki...Does anyone know if there is a train going from Riga to Tallinn??? I know Buses goes ever hour on the hour...How far is the bus station to the ferry??? as I have luggage??? Are they any lockers at the station??and I understand they are quite a few ferries crossing to Helsinki. Any advice which one is good and can I buy the ticket at the port??? or better to book in advance??? Would have like to see some of Tallinn before I depart. Are they any tour companies which takes one on the sites??? Is Protected content good to see the city center??? Or better to stay one day???

Would appreciate any input as I am planing to travel next week...

Thankx...

Farah