I have three questions
I can only play (every season) up to level 100 (is it because I don't have a Battle Pass?)
gives Fortnite some free skins that you get e.g. When you have completed tasks or something (without Battle pass and without v-bucks)
this Australian who won a round of Fortnite without moving how did he manage to get into a lobby with his roommate without being in his party?
Yes
Yes
either press Ready at the same time (works better on Oceania servers because they have fewer players) or Custom games
Without Battle Pass you can reach a maximum of level 100 (to my knowledge)
There have been free skins every now and then in the past. The last one was as far as I know, the skin that you got during the Christmas season (fir tree skin)
With luck, if you are looking for a round at the same time, you can get into a round together. So the two of them were just lucky.
Yes, it's because you don't have a battle pass
skins are rather rare but gliders, picks and these parts that change the weapon color (no longer have the name in mind xD)
if you click on "ready" at the same time (if you are lucky) you can come to the same lobby with your friends even though they are not on the team. This is forbidden and violates the rules
1. Jap that's the reason
2. Yes, but very rarely
3. You pressed ready at the same time