I have had to edit your question down to one question according to enotes regulations. Jessica is presented to Portia in Belmont as Lorenzo's wife in Act III scene 5, just as Portia is supposedly going to retreat and "live in prayer and contemplation" until her husband returns safely with Antonio. Portia is very welcoming of Jessica - she is, after all, leaving Belmont in the care of Lorenzo, Jessica's husband, and therefore clearly trusts him, and, by extension, her. Note what she says:
My people do already know my mind,
And will acknowledge you and Jessica
In place of Lord Bassanio and myself.
Clearly, the fact that Portia is saying that Jessica will have the same amount of power as Portia herself is a massive sign of the welcome and love that she gives to Jessica. She is clearly trusted.