I work for KSA currently so I might be a little biased but my thoughts are as follows:-
a) culture - relaxed, client-focused, loosely structured, non-hierarchical, and fun. The people at KSA are excellent. You will very rarely meet someone that you can't get along with.
b) Work/Life Balance - I won't kid you but the hours are long, as per any consulting firm. We work on average 9-10 hr days but the company never transmits any rules on hours. You work in relation to what you think is best for the client, and we try to make sure this doesn't mean working on weekends. Generally though it is a work hard, play hard culture.
c) Payment package - varies by country. Expat packages are available. Payment though is usually in line with the market.
d) Tips/Hints/Prep - retailing experience is useful. Describe examples of projects worked on, changes recommended, and the results achieved. KSA employs based on personality as well as intelligence so be open, honest and amusing.