After changing 1 mission for free, the color of change missions button should change to yellow just like the speed up cost of micro-upgrades.

It will be rewarded as daily gift, not as reward from mission. And they are not rare. After missions update i got DCC twice, in my two accounts, and once in my other account.

Daily Missions are like Daily Gifts, but you have to complete the task daily to get reward instead of just logging in once a day. And Daily Missions give more reward than Daily Gifts. You will get 3 missions on first day and those missions will not change on server restart, means after logging in on the 4th day you will see the same missions. You have to complete them, and you will get new missions on the next day ( if you complete only one, then you will get one new mission, other two will be same as yesterday which you did not completed) You can change any missions free once a day, and have to pay crystals if you want to change again. If you want to change all 3 missions for free, then you have to change one mission per day, and hence, on the third day after you change the third mission, you will get three new missions. You will get a maximum of 3 missions. Suppose your task is "Destroy 100 enemies", and you completed 50% of the task, you can complete the rest on the other day.

When logging into server EN7, it loads forever. I can only see the main chat, and the loading bar which keeps loading. To be able to play the game, I have to change server manually from address bar. Even then the game does not work properly ! After changing to other server from EN7, Missions and Friends tab does not work, and garage loads forever too. I have to log in to any server other than EN7 to play. If I go to EN7 server once, i have reload again, after changing server in address bar. Tried in other browser, same problem. Dont know if i am the only one with this problem. Edit - It is working now. The problem started just after server restart. Now all good.