Engineering and Ross Preferred Admission?

Is it possible to apply to CoE and Ross preferred admission? If so, how does that work? Do you get a dual degree (BBA and engineering degree)

Also, is engineering significantly more competitive than LSA?

Yes, there is now an option for that in CommonApp since a couple years ago.
Yes, CoE (or Ross pre-admit) is more competitive than LSA. The admission rate is lower (27% vs 33% last year) and the admission stat is higher.

If you are not interested in the dual degree and would prefer Ross as a first choice and COE second, then you would apply for both. Your admittance to COE is considered first. If accepted, your Preferred Admission app is then considered. If accepted as a PA, you then complete your first year in COE and move to Ross your second year.