Adding additional newel post to staircase

Hi,

We have a railing in our home which is secured to a newel post at the bottom and attached to the wall at the top. Please see the photo below:



The railing on this staircase has quite a bit of "give" to it. The post at the bottom is pretty solid (a small amount of movement) and the connection to the top is solid. In the middle of the staircase, though the railing has quite a bit of give. I think it's just too long of a run without another newel post.

So my questions:
How much (if any) wobble is expected from the newel post at the bottom?

What are the methods to add an additional newel post in the middle of the staircase? Is there a design that will support the railing without cutting it, or will it need to be cut for the newel post like the railing along the hall at the top is?

What will be involved with the additional newel post installation?

Thanks for any advice. I'm trying to decide if this is a job I can handle or whether I should bring in the experts. I have little experience with "detail" carpentry.

flamtap