So, I'm new to Fortnite (about 3 weeks of solid playing) and wanted to ask some questions and see if anyone could help me.

1. Battle Pass, I just hit level 100 and finally got the Dire skin! My question is if I don't finish the challenges for the skin (or Calamity) will I not be able to further unlock them later? I really want all variations of both skins and would be unfortunate if I couldn't level it up anymore.
2. Hunting Party Challenges, I finished 8 weeks and got the A.I.M skin and wanted to know if I finish all 10 weeks do I unlock anything else?
3. Is there any other ways that don't cost money to get V-bucks? I play Fortnite (not BR) and have gotten some that way but is there any other methods?
4. Leveling up. What is the best way to get xp and other things? I want to be able to use my time the most effective way in leveling up and getting XP but don't know really which game modes are giving me the most XP.

Thank you for taking the time to read all of this if you did, I appreciate any response or any help with these questions. Thank you!