Yes, the checkbox and text have to be in different columns. Docs is an OK word processor but you don't have a lot of formatting options. For way more features I suggest you check out newer apps like https://coda.io/ or https://www.notion.so.
Auto creating pages from a list is definitely a scripting project so look at Google Apps Script but way easier would be generating your starter docs with Python plus a plain text template then mass importing them to Drive.
However if you're looking to create a note taking system I'd say forget about Docs and look at apps that are actually for that. Obsidian is pretty well known but check out Logseq too. In these you can create a new topic with a starter page just by surrounding the topic name with brackets and clicking on it. The bracket are hidden afterward.
For headings I suppose you mean 'headers' which are the spaces at the top and bottom of the page where page numbers go. You can't add auto roman numerals for page numbers. This used to be common in older books but not really any longer. Fortunately you can still do this in LibreOffice which is a free download:
Although I can't find a fix in google docs itself, I did find a solution. I use https://office.live.com/start/word.aspx since you can go under 0.21 in. and just copy and paste it into whatever doc you're using.
You can use the styles menu to set different styles for each type of text. Once that looks good, you can "Save as my default styles"!
Hi u/Zweer1
Have you tried looking into using a google spreadsheet? It's almost similar to excel. In order to access google spreadsheet. I will share the link and if interested go ahead and sign up. I believe it's free because it's part of Google.https://www.google.com/sheets/about/