First question: Yes and no. I believe everyone should have Kevin Flynn’s skill chips as a start. No being in epic city watch, all skill chips that drop are selected from the ones that u are using. (Eg. U have at least Elsa, Hades, Scrooge, Kevin Flynn on your team). And they are selected at random.
Second question: Those that have no level restrictions is a good skill to invest on usually. However, read the description and evaluate if it is useful. (Eg. Bo Peep’s red skill. Her red skill allows her to increase armor and reality per KO’ed ally. It also gives her additional skill power and max HP and more damage from “Billy, Goat, Gruff”. See if the character is commonly used in Arena and Coliseum (if any). Alternatively, if u know any guild mates or friends who have red skills, ask them for advice as well.
U can also see if the hero is useful in combat in general. For example, Pooh can deal good damage with his white skill. His stacks of “hunny” can also slow enemies with his purple skill, making his stacks of “hunny” useful. His red skill gives him a shield and energy when “Balloon Delivery” is used. His red skill also gives him additional max HP and armor and more healing to “Balloon Delivery”.