Meals in BA First tend to be something comparable to, say, an average fancy-level restaurant - they do their best, but obviously have limited preparation/cooking facilities... Plus everything tends to taste blander in the air.
Everything in the lounges are complimentary. Munich has a shared business/first lounge with free drinks, snacks, internet etc.
Munich to US will be via Heathrow (presumably) where you'll have access to the Concorde room. Booking a longish transfer period (3-4 hours) will give you time to have a free massage/beauty treatment. Concorde Room and BA First again offer I'd say nice canteen food, fine wines and spirits and plenty of extras. Food will be better on the plane. I personally stick to the BA First lounge as the food and wine seem to be much the same and I prefer to be able to just go and grab it myself rather than having to be forced to ask the staff there. If you have enough time then visit both!