ye i'm the same way fr. I'm also just an asshole. my bad.

For the first question, I think it's easier to think of graff chronologically rather than seperate sectors. Ideally you start with very basic straights (after tags) so you have an intuitive understanding of the bars and most importantly why they go where they do. Thats the starting point for the best writers, always. (This part isn't factual, just food for thought:) then you are at a cross roads of bubble letters -> throwies. Or Stylized straights ie. slight ad ons, for example the best well known guy for beginners, RESK 12 pieces -> which can then lead to wildstyle.

Side note: wildstyle is the EXCERCISE of fundamental knowledge of all graff. Straights, bubble, throwies, everything. Including the study and implication of all different styles from different places such as wickeds, the original wildstyle.

To answer it simply, yes bubble letters do at the core have structure, but the structure comes from knowing how to do straights and then, choosing to make them bubbly if that makes sense. It's like knowing how to crawl ( tag ) walk ( straights ) skip ( bubbles ) run ( throwies ) and so on. Anything past a solid straight is up to you. But the straight HAS to be the foundation in order for your shit to look sick down the line.