Re: travel —> it’s possible but would say 10-30% if weeks of year at most. On interview process: in BCG is different than from consulting positions. For entry level is a typical corporate interview: they want to see how you think, your ability to be a self starter and independent contributor, the ability to work in team and ability to communicate things clearly. If position is experienced, they will test your specific knowledge of function/topic/industry to which you will provide support.
hope this helps,