Questions about a few things :)

I'm still trying to figure my way around this game. This sub is really helpful to me and people are nice here. (I hope my questions aren't too annoying xD)

1) How do I get more positive traits at tier 10? Do I upgrade them with a potion or is it only through breeding?

2) How can I make more coins besides daily chests? I'm at 200k now and I want to eventually buy a cute dragon I like.

3) Is there a way to get dragons from previous seasons? Or do I have to buy them from someone else? (It's completely okay to me if that's the case).

Terminology wise, sorry If I sound stupid lol. What do these mean? Ex: DBL, 4x10/9x10. Inform me as much as you'd like, I'd love to learn more about this game and community.

Some dragons I'd like to buy from someone or eventually get later in game. (If possible). Impiavolo, Amoonita, Sunfloris, Atravanta, Gualyra, Kikiken, Mielebee, and Mosuraki. I like the designs and how silly they look regardless of stats. I wanted to set a goal for myself so I don't get burnt out like I did playing HL. If anyone has any tips on how to get them, please let me know!