Unlike other schools they have over 300 seats to fill. That's double, triple, quadruple, quintuple the seats of other schools. That means interview process is long and waiting to hear back on logistics can be long.
This can be improved sure, but this is the way it is for now so just have to plan for this type of process because it won't change anything being stressed and upset.
As far as the campus assignment goes its not exactly random. Think about it, that is an awful way to create cohesive classes. What if you're more interested in research than another applicant and both of you have Indy. Who get's it?
They try to match you to your top choice assuming geographical locations (where you're from) among other factors. Most people will just select Indy thinking that's the mother ship so it must be the best, but obviously there will be more people wanting Indy because of this reason (poor reasoning) so how do you parse out the students if you have majority selecting Indy? Who really belongs there? Email them and explain your choice for your campuses and ask that it should be reflected in your application. Obviously you need to have a compelling reason for you campus choices.
If you're an OOS then email the admissions and state some reasons why one campus would work best for you and these things will be taken into account. Doesn't mean it is guaranteed, but just think about it, it's not press a button and applicant_AAMC_ID(int) = rand(campus(int, pref)). There's more human variables to it all.