solver

Open the room under the roof, review the settings on the Structure panel.

Draw in your own wall. Read about Roof Cuts Wall At Bottom and Lower Wall Type When Split By Butting Roof.

Not much to learn. You need some software -- both free and paid are available. I use https://screencast-o-matic.com the paid version, the free version works too but lacks some of the advanced features. Chief also offers a couple of viewers -- see https://www.chiefarchitect.com/products/3d-viewer/ A microphone if you want to record voice. And I agree about changing previously placed objects when defaults are changed.

Did you watch my video above that shows how that works?

What you probably should be doing is changing the wall type, and not just the exterior material. I'll often paint a brick material on to a Siding-6 wall for example for a quick visual, but because the thickness of the brick is so much different, changing the wall type is best. Windows and doors are typically trimmed and located differently too. Wall defaults apply to new walls and do not change the old ones. With Pro, I'd make a copy of the plan, select all the exterior walls and change the wall type. Then update the Windows and doors. Unfortunately, not all window and door defaults are dynamic, so some changes may need to be made by opening the objects. Using Shift Select helps. To select multiple windows, click the window icon as if you were wanting to place a window, now hold shift and marquee around the windows you want to select. (This works for cabinets and doors too). Open them and make your changes.

Watch on YouTube: http://youtu.be/PL06sZ7PsmE?hd=1

Chief Premier has a checkbox to make any wall a Partition Wall. Another option is to use a Pony Wall. Make the lower wall 1" tall and assign a material of your choice.

The program will most of the time do the correct thing on its own.

What David said, and here is why.

Could you post a picture?

Could you be more specific?

How would you change trim color?

If you use SketchUp or a similar tool, you could create the railing -- just Union Jack flag an X with a + through it, and import for use a Panel. You could do them in Home Designer from individual parts, but not so easily.

No.

Not that I know of. Really simple to take a cross section, measure and adjust.

Have you considered the Materials List?

I assumed you would know to uncheck Roof Over This Room

Go to your Dimension Defaults, change to Locate Surfaces, then pull an Interior Dimension.

Make that space a room -- close it in with Room Divider walls.

Those need to be drawn manually. Draw one, open it and change the settings, then copy it across.

The default floor framing is an I-Joist. What type of truss do you want? Why change the flange width?

Open each room, review the settings on the Structure panel.

I keep grid snaps off all the time as I don't find them useful.

Watch on YouTube: http://youtu.be/adVWNY7F10w?hd=1

Post a picture or 2 showing your railing.