Best background for 5e character who is secretly a dragon? [closed]

I’m making a character for an upcoming D&D 5e campaign who is secretly a dragon who permanently polymorphed itself (so, no mechanical advantages, just story background). Wondering what background would best reflect the fact that – rather than having a typical human upbringing – my character spent the first hundred or so years of his life as an avaricious fire-breathing gold-hoarding dragon before deciding, for reasons of his own, that being smaller and friendlier was better. My DM is open to homebrew content, so if there’s something out there already or modifications that could be made to an existing published background that’s fair game. I thought about maybe modifying the flavor of the Noble background, but mechanically I’m not sure if there’s something that makes better sense.

Does/Should the Gladiator background grant proficiency in the weapon it gives?

The Gladiator background (an Entertainer variant, from PHB p. 130-131) gives a strange weapon (like a trident or net) as starting equipment, but doesn’t explicitly specify that it gives proficiency with said weapon.

Is it implied that it does? (Or if not, should it, considering that a seasoned gladiator is expected to be particularly skilled with his weapon of choice?)

Do characters start with the tools their background says they are proficient in?

I find it odd that some backgrounds give the character proficiency with tools but then do not list those tools under equipment.

For example, the Urchin:

Tool Proficiencies: Disguise kit, thieves’ tools

Equipment: A small knife, a map of the city you grew up in, a pet mouse, a token to remember your parents by, a set of common clothes, and a belt pouch containing 10 gp

Does the fact the Urchin is proficient with the disguise kit and thieves tools imply she starts with them? Or is she somehow proficient with tools she does not own?

If you choose to roll for starting gold for your class, do you get starting equipment from your background as well?

Say you choose to roll for starting gold for your class (and then buy equipment).

Do you still get the starting equipment from your background (but not from your class)?
Or do you not get any starting equipment at all, from either your class or your background?

Is it just up to the DM?

Are class skills picked before or after your character’s Background is selected?

In the Backgrounds section:

Each background gives a character proficiency in two skills. Skills are described in chapter 7. In addition, most backgrounds give a character proficiency with one or more tools. Tools and tool proficiencies are detailed in chapter 5. If a character would gain the same proficiency from two different sources, he or she can choose a different proficiency of the same kind (skill or tool) instead.

Could a Barbarian character being created, for instance, pick Athletics and Survival as his class skills, and then when selecting a background, pick Outlander (which grants proficiency in these two skills), and then using this rule, instead pick two skills from the whole skill list?

Or is your background chosen before class skill-proficiencies?

course suggestions to learn background for sensor fusion

Specifically what topics in probability would give me the background I need to understand sensor fusion?

I’m looking for a college class that would include these topics, so I’m wondering what the class might be called or what might be in the description.

By any chance do you know of a community college that offers a good class that would cover these topics?

To explain a bit more, I’m a rising sophomore computer science major, but I’m on leave from my university because of the pandemic. I want to take a class in the meantime, and since many community colleges are online at this point, I have many options, but I’m not sure exactly what I should be looking for.

Thanks for your help!