1. Not a problem!
2. You're in the right board to ask, haha. Off the top of my head, you have Archangel, 5-1 (5-one), Blink and Mizuki, though.
3. I think the more you express that it's an opinion... phrases like: "I think this is good because..." rather than "This is good because" or... "In my testing x has been a bad MU", "I've experienced that [insert thing here] has been the best [other thing here] in my testing.", the more it seems I dunno inclusive? As for the last bit:
Express that you're looking forward to learning about the character, prompt/ask others to share their experiences (in terms of metagame development), maybe highlight things that you've observed in your study of the character, what some players tend to do more, etc. The last bit shows that you're aware of what you've seen in the past or from predecessors.
This is more important to this game compared to Brawl, where it is without a doubt that you are and expert of that game with loads of experience (your approaches to MK and Brawl writing highlight your authoritative knowledge here), whereas you are still relatively new to this one. Even if you are highly talented regardless. : )
It's more like... it shows that you're aware of the other scenes and what they're doing outside of the EC (which was something I felt lacked in the CT tier list in terms of characters --- rather than of players of a character --- in this case).