1) Thomas Cook organised the first tour in 1841.
2) Pathfinders wasn’t/ hasn’t been the first to offer tailor-made holidays. If PATHFINDERS still exists, 2nd option; if not, 1st
3) He has worked in the travel industry since 1996.
4) When did you start/ have you started working for Kuoni? Both posible, perhaps 1st option preferrable
5) Customers became/ have become more demanding in the last few years.
6) The number of bookings has fallen since the accident.
7) So far we have had a very successful season.
8) Visitors from the USA have increased by 8% since the last year.
9) We started offering tours to Mexico two years ago.
10) Many operators have put their prices up lately.
Hope that helps. Perhaps you could get other people �s opinions before deciding.