Who will be there?
Usually the employer, another executive-level person or the HR department conducts the interview.
Do we shake hands?
Yes, people usually shake hands at the beginning and the end of the meeting. It is usual to touch the other person (shoulder, arm) and, where there are women in the group, it is not uncommon to kiss each other (twice). If the Spanish person opposite you tries to give you a kiss, do not refuse it, but you should not be the one to initiate the kiss.
A tip about personal space: Spanish people like to be close and usually leave less space than northern Europeans when meeting someone.