Admitted into DGS... want to study either Business or MechE. How screwed am I?

So I recently found out that DGS has a bad rep for people trying to transfer over into CS (per reddit), but I wanted to see what your opinion was on transferring over to the College of Business for Management, or to the College or Engineering to Mechanical Engineering. I'm a little iffy on which one I actually want right now but will figure it out before registering for classes.

I'm looking for answers to the following questions:

What classes should I take if I wanted to declare a major in either of those Colleges?

What kind of grades would I need to get to have a competitive application?

What else can I do on-campus to make my application more competitive?

Would it just be better to attend CC to get my GenEd's out of the way?

Any sort of anecdotes/experience would really be helpful. I'm basically freaking out right now.

Edit: I'm really starting to hate the culture of settling because of not being able to get into the major you want. The silo effect is real. Thanks for the replies.