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You should consider creating a new template once you have things setup as you like. That way, all new plans will pick up your defaults. I posted a how to in Tips & Techniques. Search for template. Dimensions in general. I would recommend you experiment with using Temporary Dimensions to locate things. This will keep the clutter down. Once you have things positioned, or as needed, add manual dimensions. Here I placed a window, clicked on its interior side and temporary dimensions allow it to be positioned. You probably want to set your dimensions to locate wall surfaces too. Edit>Delete Objects Choose to delete Auto Exterior Dimensions and the program will ask if you want to turn them off -- say Yes. You can turn off Auto Roofs there too. Not auto interior dimensions. I'm a bit confused. Maybe a couple of screen captures would help show the problems. Your window size does not include trim. For example, the 32" wide window shown above with casing would be 37.25" to the outside of the casing.

One click to place a dormer in your plan using Suite 2021. Because your version lacks the tools, you need to do it the hard way ... I know that's not very helpful.

What's your goal? That is, why are you doing this? You cannot work just part of the model with your software. As you have seen, it's all tied together.

You could not open it.

Not too difficult, but it's what I do Make a copy of the plan. Set your plan defaults. 1st floor ceiling heights etc. Start with Edit>Reset to Defaults. Choose All Floors and check all boxes below. Set the default pitch in the Build Roof dialog and uncheck Ignore Top Floor. Check Auto Rebuild. Make the Attic room Unspecified and set its ceiling to 1.5". Set the ceiling height in the room over the garage to 24". Set the walls as required to Full Gable and set the pitch for the roof planes that are not the default. Draw in the walls forming the dormer and set the room they form to the default ceiling height -- 8' ? Make changes as needed.

All auto built roof.

Then you will need to rethink how this is built. When I rebuild the roof, everything changes, and to get a dormer, the roof has to rebuild. Have you considered an upgrade to Suite? i have no experience with Interiors and it does not even seem to be available today. The basics are simple. Make a room where you want the dormer. break the front wall and set the pitch. Set the side walls to Full Gable. Build the roof. You will need to uncheck Ignore Top Floor.

You don't have the 2 dormer tools I mentioned above?

You could create the shape, but not with cabinets. This is a slab. You could put a toe kick under it and add countertop.

Try Edit>Reset to Defaults You will need to rework some of the 1st/2nd floor stairs.

Curved how? Pictures?

Here is a search link to topics on ChiefTalk. Just remember they will/may suggest things not available in Pro. https://chieftalk.chiefarchitect.com/search/?q=bullnose Moldings will pose a problem. Think about using a Custom Countertop for the radius corner. You can attach a molding to it if needed.

Nothing automatic in any Chief/Home Designer product. You can do it manually, corner by corner.

Rebuild the foundation.

That video is for Chief, not Home Designer. I see no direct control over rail profile in Home Designer. It looks like from your image above you are using Panels. If so, you may be able to build a railing in another program like SketchUp and import it for use as a railing panel.

The article you linked is completely different than what you want to do. That ability is only found in Chief, not Home Designer. Try using a Custom Backsplash.

That's all you do.

Library>Install Core Content

I seem to have the opposite problem -- spinning when I don't want it. I once suggested that spin speed be selectable. Don't know of any way to control things.

Think first about using interior rooms to control the roof, not about getting walls/rooms defined as they are in the actual house.

Change ceiling height, walls will follow. No direct control over non railing wall heights.

Keep auto rebuild roofs on until the roof is correct. Roofs build over rooms, so focus on the roof first. Once it's correct, then turn off auto rebuild and work on the rooms. It looks like your default roof pitch does not match the house, the garage roof is too low etc. And why draw the house with the front at the top of the screen?

Rebuild the roof ...

Have you checked the website for a viewer? Many people have a Dropbox or similar account that may be used for transferring files.