Will this outside zip pocket fit a .38 revolver?

Yes. I have a S&W 642 Airweight. Without a holster, it fits seamlessly and you can draw it out effortlessly. I am right handed and carry my purse on my right shoulder. I can use my right hand to unzip the compartment while I am still carrying the purse on my right shoulder, and stick my right hand in and the revolver is perfectly positioned for me. The grip goes right into your hand. However, I like to keep mine in a sticky holster, and the holstered revolver fits , but if I don't use my left hand to keep the holster inside the compartment when I draw, the whole thing comes out. I plan to rectify this by getting some velcro and attaching the holster to the inside of the compartment so the holster stays put. The bag is well constructed and there is no printing for that reason. I love this bag, very nice quality and does not scream "CC". I will say that a lot of this bag's functionality as a CC bag will depend on which shoulder you carry your purse, and on which hand you shoot with. You'd need to think about how you would carry it, and where that zipper would be positioned as a result to see if it would work for you. Great quality, I plan to buy another color I like it so much.

Will a 13 inch laptop fit?

My 12" macbook fits, along with several other things, but I don't think any larger computer or tablet would fit, as the zipper is close to the top of the macbook.