Some agents specialise in working with foreign clients, others have little or no experience in this area. Clearly buying a house can be a complex business and getting all the answers and clarifications you may need may be hard if dealing with the latter.
As you would expect estate agents work on a commission basis. The commission is paid by both the buyer and the seller and is normally equivalent to about 1% of the purchase price of the property. The lease is generally signed between the property owner and the buyer, a process which is overseen by the estate agent.
To avoid misunderstandings caused by language or other make sure everything is down in writing. Don’t take anything for granted: always ask until you get a satisfactory response to your questions!