Thanks for questions. I'll try to answer each in turn.
A post with a plate at the bottom, and a fixing/mount at the top. The whole thing needs to be vertical at all times, however the fixing/mount at the top is pivoted so that it can accommodate slopes
Probably the easiest solution for this is to have a separate post and mount and attach the mount to the handrail geometry so that they both follow the path together.
Glass fixings. Some simple, but nicely detailed glass clamps that will attach the glass middle section to the posts.
The glass clamps can be used with the post in a corner and evenly input slot by using a combine operator. Because they are still computed separately from the post they should revolve to follow the base spline. Use left/right padding to adjust the distance between the post and the brackets and between the brackets and the glass. The examples in our library use this technique.
A glass middle section - self explanatory really. Doesn't need to curve around corners at all, but will need the edges to be bevelled.
The glass should go in the default input slot. I'd use scale mode and to avoid the chamfers getting scaled they ends can detached and added to the combine operator used in the corners and evenly inputs.
Can I have all of the above items as separate pieces and make this work?
Where it's possible it's good practice to keep things separate to allow for more parameterisation opportunities with RailClone. Of course that's not always possible, and may make for a more complex RailClone object. In this case I can't see a problem with building these as individual pieces. My general approach is to try and break things down into the smallest repeatable elements. However I've attached a simple and complex example to illustrate both approaches. In the example I've attached the clamps to the glass as you suggest. The disadvantage of this approach is that the clamps scale with the glass which could be noticeable if the spacing between posts is too large.
It is quite important that the glass clamps don't curve around corners (fillet), though the handrail at the top does need to. How do I achieve this?
To achieve this I'd build the RailClone object from two L1S generators, one for the glass panel and posts and a separate one for the handrail. That way you can adjust the fillet separately for the handrail. I've attached a simple file to try to demonstrate what I think you are trying to achieve. (excuse the quick modelling, it's not as nice as yours
If you wanted to send us your style so that I can look in more detail at your particular case and help further please feel free to either attach here or send to firstname.lastname@example.org.
Hope that helps,