Yep! You may as well invest in getting all of your equipment out of the way.
I have had the same Brinsea for years so it will last a long time. When you get it home, practice adjusting the table up and down to get it loosened up so you won't be fiddling with it when you have chicks that need to be under it. You have to hold your mouth just right when you first start adjusting the table height on those things
but they work beautifully and are built to last.
A soft shell every now and then is normal but since your girl has not been laying it could be sign that she has a problem in the reproductive department. You are taking the right steps to make sure she is getting enough free choice calcium. If I were you I would not add extra to the feed, the reason being is that you don't want the other hens who are not having problems to develop kidney problems from too much calcium. You can also give offer some phosphorus in the form of bone meal to your laying challenged hen as both phosphorus and calcium are needed to make the shell.
Since you are investing.....LOL... Order some of this, Ropa Complete: https://www.strombergschickens.com/product/Ropa-Vet-Poultry-Complete-500-ML-Bottle/New-Products This product is super!! It helps with everything!! I had a hen a few years ago that kept laying soft shells regardless of diet so I put her on this and her eggs hardened right up. WARNING ABOUT STROMBERGS'S website....don't start looking unless you have an hour! lol That website is Chicken Disney World.
I am not trying to be the harbinger of doom but I feel I need to let you know that your girl might have a reproductive issue that will eventually lead to internal laying. Internal laying is pretty common and is the precursor for conditions such as Egg Yolk Peritonitis. For now though you are doing all you can do. Just keep up the good work and keep monitoring her eggs. She might snap out of it especially with the Ropa in her water. And remember we are here to answer any questions for you. If there is something pressing, you can always text me for a faster answer. Also, you should be getting your Chicken Health Handbook today right?? I promise you will sit down with that thing and when you get up you will have a chicken health education.

Do you make your own milk kefir? If not I will be happy to share my grains with you. I give it my girls about 3 or 4 times a week and they have the prettiest poops and hardest eggs you can imagine. As a matter of fact, I dropped one on the carpet yesterday from about 4 ft and it didn't break. The egg that is not the poop! lol
Yes, you are correct about the cedar shavings, do not use them. They contain all sorts of things that are irritating to the respiratory system of chickens. I always use that spongey rubber maid shelf liner with several layers of paper towels for the first week..week and a half in my brooder. After the chicks have established that they know what their food is you can put pine shavings in the brooder. Bless their little hearts they can eat pine shavings when they are a few days old because feed gets spilled in the shavings and they do not know not to eat it.