"Robert11" wrote in message
Moving into a 30 yr old split level house that has the staircase banister
"assembly" between the floors made from rough pine. It does not have
baluster posts to the step level as a modern railing does; rather it uses
fairly closely spaced square post pieces from the top hand rail molding to
the level of each step, at the edge, where it is fastened to the side of.




a. My main question is whether one can buy pre-made sections to install,

I've never seen them, but that does not mean they don't exist.



Or, is this approach not practical because all staircases, probably, have
a different slope ?

Similar, but they can vary slightly.


b. Is this screwing it in from the side at the bottom approach used any
more,

Sounds ugly and cheap. My outside deck is like that, but I'd can understand
why you'd want to change the interior rails.



or are all modern banister installations done by fastening the balusters
thru their bottom ? Why ?

Some balusters are more or less set in recesses rather than attached. I don'
tknow if any codes exist on that.





d. Before trying to find a carpenter, I would like to learn a bit more as
to what might be available, and different approaches to consider. Any
thoughts on this would be most appreciated.


Look for a real lumber yard that carries that sort of thing. Not Home Depot,
but a real place that carries what you want to see. You can buy al the
components you need, various styles, etc. My local lumber dealer was most
helpful when I replaced mine.