IIRC Martin signed a new contract with the Cats to enable them to take advantage of his lowered points. Whilst I have no details I doubt it was a one year deal. Keep in mind that his strengths are ball-handling and defence, he's not the scoring dynamo that many teams want at PG. If he leaves the Cats for a new team, he'll have their fans bitching that he doesn't score enough.
I have no facts to say that Jawai will stay in Perth, but it remains far more likely than him going to Brisbane. Assuming he's on a one-season deal, he can go where he likes, but Brisbane doesn't become more likely just because Perth-haters wish it to be.
Perth have the money to pay him, and the structure to support him. Knight at PF, and Jervis to back up means that Nate can play his game and have an impact for 20~25 minutes. As I said, anything is possible, in the merry-go-round that is the NBL he could wind up anywhere next season, but unless Cairns suddenly have an influx of cash and talent, Perth remains his most likely team.