Stairing advice required

[Spr0cket]

I've never worked on stair assemblies before so thought I'd consult some more knowledgeable folks ...

I am busy prepping out hall and landing for some decoration. Part of this is oak flooring. I thought I'd like matching stair rail and balusters, but how to accomplish the desired result is the challenge. I've found a stopped chamfer design of baluster, along with matching newel designs etc. all in Oak.

Tearing out the existing gloss painted balusters is easy enough, as will be the hand and base rails.
My challenge is the newel posts top and bottom... They are presently finished in what I would call a mahogany color of stain 9 which after a very brief sand of a face, appears to have penetrated well. So the idea of matching a new oak upper post to the existing bases seems aestethically to be a no go.
Any ideas on how I could achieve the end goal - does it require me to remove the exisitng posts completely and mount new items?
If so, how are the posts typically secured - I can see the stringer is dowelled (and likely glued I would expect) into base newel - hows does that get affixed to floor? Upper one looks even more fun with the stringer and the riser looking to be morticed in.
I have a reasonable selection of tools from cabinet work etc. but having no experience of stair construction - wanted to seek some advice before I started any plans of attack.

Am I best off calling a joiner in - if so, any simple estimation of what duration a job as vague as my definition would entail?

House was built in the 80's if that helps identify what practices would have been employed around that time?

Thanks in advance for any suggestions or advice on possible approaches.

 

[regsmyth]

I'm in the process of fitting a staircase - it's been quite involved, and things have to be done in a fairly methodical order.
As you say, the stringers are tongued into the newel posts. And glued, and dowelled.
The middle newel post, which has stringers coming into it from two sides, had to be fitted as the stairs went in. You couldn't "put the stairs in", then add the newel.
The top newels are generally notched to sit over a joist or trimmer. They aren't necessarily mechanically fixed, they just sort of sit there, hooked onto the trimmer.
The handrails are also generally tenoned, glued and dowelled into the newels.
They are then normally covered up/plasterboarded, floor boarded etc etc.
The point is, I think, that replacing the newels is quite possibly only feasible on the bottom ones.
To replace all the newels, you would need to virtually take the whole staircase out, in order to chisel away the newel from the stringer, and in order to get the new ones on.
Frankly, I don't think your idea is very do-able. But maybe someone else can offer a more "positive" response.