We have already had many issues with copy write works that we only allow them on the amateur series. They only way they are allowed is when the image is drastically changed. Unless the creator has said you can do this then its ok, but other than that no. I do fan art but keep it away from here, and display it elsewhere.
As far as im concerned there is no limit but dont do it all at once.
I am unsure how this site promotes artists, and ive been an artist for 12+ years. I havnt had a splurge in likes or followers since being here, but if you have linked your art back, people can look at it. I dont know if you can put links in descriptions, i hvant seen one and i dont think people do, but thats just what ive seen. people do link their deviant art, instagram, FB page on their profile, or try and look up the artist, some have their artist names on here.
Plus theres a saying in art school, "Sometimes you have to do a lot of free art, before you get recognized".