They may depending on the numbers. If you have lets say a 14/55, you will get some lift for replacing them with 16/58 or numbers higher. The higher the numbers, the stronger they are related to weight, the more lift.
A bit. Some prefer it even being a little stiffer because it will help with the nose diving when breaking and firmer turns around corners instead of being softer and "mussy". I just ordered Rubicon take off shocks from a member here and expecting them this week. Overall I heard they are a nice inexpensive upgrade.