Thanks for your questions.
1. Yes, both the FOX and Öhlins Shocks fit with stock springs. If you buy the Öhlins, you’ll need to be sure to select the option "For Stock Height”. You can find the product by clicking on the following hyperlink:
2. Stock springs are variable rate. By “better,” maybe you’re referring to ride stiffness. We haven’t seen springs on the market that are softer while keeping the stock ride height.
So the options are either keep your stock springs to match with the FOX or Ohlins or change to lift springs like THOR or ORC-Eibach, both of which offer a softer ride. However, please keep in mind that modifications to a stock vehicle will often result in noticeable differences in how the vehicle rides. When you change to softer springs, the tradeoff is that your ride will feel softer, but it will be less able to handle cornering sharply like a stock ride would. It will handle better off road, and less so on the street. On more powerful trucks, you may feel body roll and consequently feel the need to help stabilize your truck with a rear stabilizer bar.
For purposes of simply softening your ride, you can simply change the shocks since most of the comfort you’ll experience in a change of suspension will come from the shocks (roughly 80-90%).
Please let us know if you have further questions. We're happy to help.