You could take a look at this article. It talks about padding numbers with leading zeroes which you may be able to modify with a calculated column.
Below is the general idea, slightly modified to your situation.
Column1 is the field of your first ...
No this is not possible. Sharepoint Platform does't have an field level security. You can do some smoke and mirror solution with Infopath\PowerAPp but nothing will stop user from creating a custom view and modify the content directly in the list. For some cases such solution is enough.
Does it have to be entirely in SharePoint? Why not build the page out using exactly the things that you know, HTML/CSS/JS and make all of your connections to a SharePoint list?
Edit the form in SharePoint designer.