Hello there,
Yes you don't need German at all (although it's nice of course), but think how teachers manage in a multi-national class - they have to use English exclusively and use diagrams and actions to explain things.
You can either buy a clip art software, or you'll find free flashcards on many sites - here's one I found recently - the flashcards are a bit naff, but they get the job done!
www.eslhq.com
Also try some of my games - meant for kids - but it might loosen up some of those stuffy business men (hoping they are not, in fact, stuffy) - and they are just the ticket for beginners because they give you varied ways to present and practise new vocab and simple sentences.
You can try some free by signing up on
www.teachingenglishgames.com
Kind regards
Shelley