Welcome to ‘It’s Foss’ @BenderClark. Are you looking for recommendation for the size of each of these partitions?
You will get lots of opinions for these. But I will give you mine, but others may not agree.
This is because it is a personal opinion and also on how you use your system. I am running Linux Mint Cinnamon 20.0 on a Laptop.
My root partition is 30 GB with 10 GB free.
My swap is … 4 GB. Linux does not swap much.
My home is … 50 GB
TimeShift partition of 60 GB … allows 5 or more TimeShift snap shots of 7 GB each.
My recommendations for you;
root -----> 50 GB - This will allow for at least 3 TimeShifts
swap ----> 4 GB – again Linux does not swap much.
home ----> Big as you want.
Remember, you need a backup / restore procedure for your system (root) and data (home) areas.
i would recommend repeating that part of the process. the bootloader can’t go on the wrong drive it it isn’t in your system.
my system also doesn’t swap much, but the size you choose also may depend on whether or not you want your system to hibernate. i have never separated root and home. i just try to make sure i have a relatively recent offline copy of /home in case my disk goes boom.
When you select “Something else” during the installation process, it will only do what you tell it to do. So if you only choose stuff from the correct storage medium, then it won’t touch any other media.
Well, anything can have bugs. So technically yes, it is possible that the installer can still fiddle around, however it is not designed to do that.
So I guess I should change my wording to:
If the installer is working as designed and does not contain bugs related to this feature, then it will not touch anything else, except what you are explicitly specifying, when you chose the “Something else” option.