Hi Jakesbro2007
I don't think there are definitive answers to those questions....some things can maybe be implied from the things they say or do, but in the end it's mostly subjective. There are discussions on both topics to be found on here...maybe someone can provide you with links to those threads
For what it's worth, I think Jack's parents had some idea that their son may have been gay and I think his mum knew that Ennis was the person Jack loved after Ennis found the shirts and brought them back down the stairs. I think she had known they were there and had an idea of the story behind them...Ennis taking them confirmed that the other shirt was his and therefore he was Jack's "other half"
As for Lureen, again I think she may have had some inkling, possibly from knowing the truth about the way Jack died (or possibly not...I'm unsure about that!) but she didn't know about Ennis until he told her that Jack and him had met on Brokeback. At that point, she put 2 and 2 together - Jack's favourite place...they met there...he was always so happy when he was going to meet Ennis...and realised not only who Ennis had been to Jack but also that it predated her relationship with Jack.
That's my two pence worth, anyway!