congratulations sam! they're not silly questions at all. as far as I know:

1. i can't see why not. it's only when you're ttc that it might be a problem since it's hostile to sperm.
2. frozen food should be defrosted in the fridge (or microwave) then cooked asap once defrosted. so yes, enjoy your chicken!
3. yoghurt is fine. avoid feta, ricotta, brie and camembert unless thoroughly cooked. google 'listeria' or check out the aus & nz food standards website to find out what's not advisable to eat.
4. home-made salad is fine - the general idea is, when you're eating out, don't eat stuff that may have been sitting behind a counter all day.