Chopsaw

No just an auto generated Mono Slab perimeter and then manually placed Slab Footings to divide it up.

Yes keep going. It looks like your slab footings are a little narrower than mine but that is just defaults. Get them connected and create your grid.

Yes. You should find it with your wall tools.

Just as I said. It is a Mono Slab with added Slab Footings on the foundation level. Bottom view shown.

Mono Slab with Slab Footings perhaps ?

True. I also saw that in the DWG fie. I just don't think it is in a transferrable format. It would be nice if I was wrong and it would be worth pursuing if someone else knows the answer.

All three screen shots show that there is no "Terrain, Elevation Data" therefore flat terrain. I am not sure your posted files contain any transferrable elevation data. I think you have a lot of manual work ahead of you unfortunately.

If there was a chance to do it over again I think that when you initially import it will come in and everything you just imported will be selected. Ideally you would move it to a clear area at that point so you could work with it without interfering with your other work then bring it into position when you are ready. You have a lot of layers in the imported DWG but I think it would be wise to keep those active since you have a lot of complexity to deal with. I am not familiar with HD but there are likely many ways to accomplish what you need in Premier. Perhaps someone who has HD experience can chime in here. There are a few people here that work both forums such as @solver or @DavidJPotter Otherwise you would need to post that specific question over there.

Sorry select everything you have imported from the DWG file so it all moves together. If they are overlapped with your work you may need to turn off or lock all those layers or just create a layer set that only has the DWG layers turned on.

Here it is in the viewer but you will want to do it yourself so you can zoom in. There is also a Layers dropdown. Fortunately it looks like your scale matches so you just need to be able to select everything and then calculate how much rotation is required and then do a point to point move to put it where it needs to be providing you have those tools in HD. Take care of that finger and don't cut metal without clamping it, but you know that now I guess.

You may need to snap some cad arc's to your wall surface that you intend to use for measuring and then use a referenced macro to display the arc length. A little complicate though as you will likely find that measuring to center will give the most accurate results for layout then work out from there.

Almost everything in gray is elevation data. Do you have a PDF of this from your surveyor ? That perhaps has a key that tells you what all the codes mean otherwise you will need to use your knowledge of the site to determine what the short forms mean. Some are obvious but maybe not to someone who has not been on site. Just guessing "NG" might be Natural Grade, you have trees marked with their species and diameter, fences and fence lines, "GB" might be Gabion Basket. You will need to be careful though as some may not be measured at grade so they can not be used as terrain elevations. Get yourself a free copy of Autodesk DWG TrueView so you can have a quick look at the file the way it was meant to be displayed before you try importing it to Chief. https://www.autodesk.ca/en/viewers

My apologies. I am not sure I have seen any sort of issue like that where an un used layer controls another layer, at least recently. What version are you using and can you post the plan file ?

I can turn it off, but the ceiling issue remains Did it make any difference to your plan view as posted above ?

You keep asking the same question but I have run out of different ways to answer it. Ceiling Break Lines.... Your roof is too low !

Did you try turning off the Walls, Beams layer ?

True you can not select or delete them but they have their own layer so you can turn them off. They do not cause the issue, they are there to indicate that there is an issue that you need to be aware of and may need to fix.

A screen shot would be helpful but that sounds a lot like a "Ceiling Break Line" which have their own layer "Ceiling Break Lines". You can turn them off but before you do that you may want to raise your roof plane and check your roof structure thickness to avoid infiltration into the room unless that is the look you are after.

Use ALDO to determine what layer it is on in the view that it will display and then make sure that layer is on in the view where it is not displayed. If that does not work you may need to post the plan file. It could be a Material or Draw Order issue but there is not enough information to know.

Potentially a high poly symbol or material that was added ? Check your "surfaces" count in the middle of the status bar in an active 3D view. Then check what it is in a backup plan file from yesterday. Check the overall file size as in comparison to the backup. Also sometimes things just get fowled up and a "Save As" will reduce the file size a resolve the situation. Surprising no recommendations from tech support especially if you provided a copy of the file ? I assume that RTX 3080 is in a new computer but knowing the specs and the size of the plan file would be a big help.

I was getting essentially the same thing with standard render. I normally use vector view so had not noticed the issue but it would be great to figure it out for material viewing. Seems to also be a PC and Nvidia issue if that helps to not narrow it down.

https://www.chiefarchitect.com/products/samples.html

Not yet unless you care to separate your schedule by rooms or floors to help keep things organized in smaller batches.

Likely line weight and color here:

That is not a default it is simply an " Angular Dimension ".