If you use Chrome/Edge/Firefox and your browser is logged into a Google/Microsoft/Mozilla account, everything will sync over to the new installation. once you log back in no other action required. If you don't sign into a browser you can export your bookmarks as an html file and then import them into the new installation. This can be found under Bookmarks in Settings typically. Not sure about saved password, as I don't have any passwords saved.
No Reason to make a list of desktop icons either, what you have on your desktop is located in C:\Users\USERNAME\Desktop, just copy that whole folder.
Again, not sure why you think you need to buy Windows, you don't. The computer came licensed with it, you've already paid for it as Dell past the cost down to you in the final purchase price. Download the Media Creation Tool directly from Microsoft from the link I posted earlier and create a bootable DVD or USB flash drive, preferably use a flash drive as it will be much faster. Windows will automatically activate upon installation.
The Crucial SSD will definitely work. However, if your laptop has an M.2 slot that supports NVMe that would be the best way to go. A SATA SSD will be a million times better than any HDD, but if your going to do this, why not go all the way and go NVMe if you can.
For every day use, web browsing/email/word processing 12 GB should be fine. More RAM never hurts and there is no reason not to max it out. As I sit here, my desktop computer hasn't been rebooted or powered off in about a week, current memory usage is at 6.3 GB and I have two instances of MS Edge open, one with 6 open tabs, one with 13 open tabs, Outlook is open, mRemoteNG (a remote desktop manager) is opened with 3 active RDP connections to servers at work and various Symantec Endpoint and Adobe CC services are running in the background.