My first question is about building your biceps. I don't really do a ton of lifting just curls and such, but I've noticed that as I do bicep workouts the muscle seems to be larger on the inside than outside. I figured it was normal but as I continue to lift it just keeps growing larger on the inside of the bicep and is the same size on the outside. Is this normal or do I need to do a different type of lift?

Also I'm looking for recommendations on the best ab workouts. I don't have a bench or anything so preferrably different types of sit-ups

Thanks.