Open Query with Progress DB/Locking Tables

Hello all,  looking for some insight on a Progress Database and Linked server  that uses OpenQuery against the Progress Database.
I am new to Progress so please bear with me.  

We use open query to read records from a progress DB, and it looks like it is locking the tables when the query runs which is impacting other users that are using the application tables.   (there is a select and update within the Query).
Our Database person  says we need to use the  @TRANSACTIONISOLATION SERIALIZABLE.  
@TRANSACTIONISOLATION UNCOMMITTED READ or @TRANSACTIONISOLATION COMMITTED READ or @TRANSACTIONISOLATION REPEATABLE READ or  @TRANSACTIONISOLATION SERIALIZABLE
2 questions:
    A. is there a way to show the locked tables
    B. What is the method to use to select records out of the Progress DB with open query.   Also, in that process there is an Update that takes place on a Transaction table.
          Can the Transactionisolation be turned off/on within the Query.

Any help would be appreciated.