Will increasing the number of shards to utilize more CPU and improve performance?

You might want to look at my reply in a recent thread here... Cluster topology consideration

The key point is that you are likely to be limited by disk IO and memory, long before CPU is a concern.

Your indexes are pretty large so index speed will be impacted. If this is time series data you should consider daily (or some other time interval) indexes, which are also discussed in that other thread.