One thing that would definitely turn me off is poorly-researched names. IRL, names aren't always meaningful. My first name, Erik, means "ever ruler" in Old Norse, and I'm not the ruler of anything. Also, it's jarring to see Japanese characters in realistic settings with names like Ichigo, Rin...
TBH, only RPing characters who are like you is extremely boring. It's fun to try to put yourself in someone else's shoes, to experiment. There's lots of character archetypes that are fun to RP as. I'm male, but I enjoy RPing as female characters. I also enjoy RPing as characters from different...
I'm 29, which means that I'm considered "old". I've been RPing on other forums since I was 18, so I've been doing RPing for a long time.
There's no age limit to RPing as long as you're having fun.
There's nothing wrong with drawing OCs/FCs yourself. Even if it doesn't look like a professional artist did it, it's still better than nothing.
I draw a lot of my own art even though my artwork is terrible. On one fandom wiki I'm on, dollmakers are banned, so users have to draw their own art.
I think it's okay as long as you're respectful and don't play into stereotypes. Even though I'm white, I have characters of many different races and I've RPed as characters of different races on other sites. I make sure to treat everyone respectfully regardless of race, gender, sexuality, etc...
I'd really love to RP as Gil from The Tower of Druaga on here. (FTR, The Tower of Druaga is an old arcade game made by Namco.) I did on other sites years ago. Maybe for a crossover RP or something.