Help with sheet music symbols/questions...

[m1u2s3i4c]

(Hi, this is my first post on this forum  )
I'm still a beginner (I haven't even used a pedal) and I have questions about some symbols that are in sheet music.
1) sim. means same as before and similar right? Which do I apply the sim. to? the individual note it was written after or the whole measure? Do I play it like double bars or do I play it throughout the whole piece? (BTW; this is on the "Arabian Dance" from the nutcracker - https://makingmusicfun.net/htm/f_printit_free_printable_sheet_music/arabian-dance-piano.htm if you can check it out)
2) I play on a Yamaha keyboard and in the screen where it shows the notes you played what does "8va" mean? because if the note is to high or low it shows the note lower/higher on the staff and says "8va"
3) Why are some pieces (like the Arabian dance from the nutcracker) are named after Arabs? I'm just curious about the history behind that (by the way I've never watched or even KNOW what the nutcracker is about  Yeah, I don't deserve to be on this forum)
4) what does Leo mean in sheet music?
5) Are big, alligator signs (I don't know what they called) mean "play louder?"
6) What does leggiero, cresc, dim. e poco rall, and risoluto mean?

THANK YOU  , I may have gotten some terms wrong, but as you can see, I'm a beginner