New With Questions

Just a few questions.
I've read the guides and the FAQs and they didn't answer my question, I also wasn't sure where to post on the forum since I couldn't see a Help section.

1. Can you change your username? I used my iPhone and it autocorrected my username without me noticing. I only realised when I saw my new name at the top of the screen that I saw there was a problem.

2. What are the 4 slots when you go to upgrade? If I go to upgrade the warehouse it says Upgrade but there are 4 slots to upgrade. So say for instance I upgrade the top slot to level 1. The bottom 3 slots still say level 0. What's this?

1. ask the support for your server whose username is supportXX (xx is the number of your server)

2. you have to upgrade each of those four individually

How do you know which server you're on?

What is the point/benefits for having 4 things to upgrade per building?
Do the 4 slots combine their output?

the 4 slots combine there output,

and go to general>management>scroll to the bottom of that page