"It has a beautiful tail."
Translation:Ĝi havas belan voston.
Esperanto leans more English on adjectives, but it's not wrong "per se" so it shouldn't have counted you wrong; that said, I'm pretty sure that is one of the things the course creators didn't bother to make sentence duplicates about, so you need to start using the common way (adjective + noun), or you'll be getting a lot of answers wrong and spending a lot of time making reports.
P.S. A suggestion: send reports for this issue only on small, beginner level questions like this one. That way people will learn that its possible to switch adjectives and nouns before the sentences get more complex (and to help the course creators, who I'm sure are pretty overwhelmed already).
Most word orders are okay, but SVO and OVS are the ones you'll see in the sentences - not all because each single correct answer has to be input in the software. If you feel your answer should have been counted as correct, use the "Report a problem function" which shows up directly under the question box after you've submitted an answer.
Regarding your second question, the answer will vary according to medium (phone, tablet, computer) and operating system, but you will find a useful link in this thread: https://www.duolingo.com/comment/8841170