What if I want to throw in a jazzy chord different than the chords on the chart or I want to improvise? Does the bass player need to follow me?
If he's a professional (not a novice) he should be able to follow you, but usually these things are practiced before they're done in public.
If you're constantly changing things mid-song, you may build up tensions with your bass player.
If you're not able to practice with your band at a time when there are no singers then you will want to communicate with him during service. Also, ask him if changing the direction of the music--as you're doing--presents a problem. If it does, ask him what you two can do to accomplish what you want to do.
Communication is key in a band. You all have to learn each other's playing style. Once you know that, then you'll see this freedom that you're trying to accomplish.
Lastly, sometimes it's good to play straight, if you're trying to throw jazzy stuff in every vacant place of a song, then you may start to give people the impression that you're show-boating. When you have a band, you have to work with the band. It's a team. Don't do that, and you'll start to see confusion or your band members leaving.