You will only receive the rewards obtained from each island after you pass each checkpoint of the Trick-or-Treat map. 
In other words, you will only get the rewards every time you make one full circle around the map.

I checked Client vs Browser.
Only the Leader can buy an additional member slot, and it will ONLY work on the Browser version of the game. Not on Client.


Please fix this, and add this option to have Commander rank in the Clan to be able to buy new Slots as well.

I'm pretty sure he means Gear Score
 
It means he/she is wearing weak equipment. He could be a troll or a player who hasn't upgraded his equipment who was somehow placed into the battle due to the MM system.
If you know the player's combo or something close to it, [Ratings (Search player username if you don't know)] to check his Gear Score. I recommend reading this article, Gear Score, if you do not understand how the GS point system works. It comes with a nice calculator for your own use as well.
There is also some strange bug going around with broken Rank Limits in the MM system. This morning, I was the only Legend in a TDM battle and the rest of the players were ranks around Major to Lieutenant General. It was pretty sad.