Welcome to Bloxburg
"Why did I get banned?" The exploit detector is not always accurate. It sometimes bans innocent people for doing random things. Also, did you let anyone use your account? There might be a high chance that someone else used your account to hack/exploit, thus banning you from Welcome to Bloxburg.
"What to do if I get banned in Welcome to Bloxburg?" If it is a permanent ban, then you probably cannot do anything about it. If it is a time-limited ban, and you got banned without any reason, you should have a button named Appeal in your ban message. You can click the button and further appeal.
"Where is the giant seashell and how to get it?" The giant seashell is in the waters under the observatory. To get there, either swim from the beach to under the observatory or jump down from the observatory. The giant seashell only spawns sparsely, though, so keep that in mind while looking for it.
"What job should I get?" It is really up to you. All jobs are rather boring as they are nothing more than a combination of WASD, E and clicks. Delivery yields the most money, yet it takes the longest time to deliver a pizza as compared to other jobs.
"Help! I accidentally deleted my item! What do I do?" There is an undo button in Build Mode. (Unless if you got out of Build Mode, then it's gone forever.)
"Help! I accidentally bulldozed my house! What do I do?" Sorry, you can not undo this.
"How do I become staff?" One must do respectable and constructive contributions in order to become staff. What rank you will get will depend on what you do and the magnitude of the edits.
"What do I do if a rule is broken?" See this post.