What is the significance of her husband's heart trusting in her?
Malbim (Derech ha'Muskal): The heart is the power that rules in the Nefesh. "Her husband" is Sechel. His heart wants to rule based on the counsel of Sechel and Chachmah. If she is an evil wife, she is not drawn after his heart's counsel. Even when she listens once, and he gains spoils, afterwards she returns via desire to oppose its counsel, and squanders wealth. All that Sechel gains to understand Torah laws, his evil Nefesh, which is Mezanah after its Yetzer ha'Ra, causes it to be lost. When the Nefesh is good, his heart trusts in it. He will not lose the 'spoils' that he gained in investigation and deed.
What Shalal will he not lack?
Rashi: He will not lack any good.
Rashi (31, according to the Mashal): He eats the Peros in this world and in the world to come 1 .
Malbim: Refer to 31:11:1:1.
Pe'ah 1:1 lists Mitzvos for which there are Peros in this world, and the principal remains for the world to come. Perhaps Rashi discusses other Mitzvos; even if the principal is not intact for the world to come, there will be Peros. (PF)