I am not aware of any stated limit for subsistence, the £200 is for the room only. The other limit I know about, referenced in previous posts, is a £50 limit on taxis, plus the frankly bizarre refusal to pay laundry costs (so you best buy new clothes instead.....).

The Regulation says food and drink must be provided, so we're down to the reasonableness test. Since there is a theoretical risk of challenge you should only buy the food and drink that you would pay for if it came out of your own pocket / insurance [just as you would have to do if it was an AA booking to USA, for example]. The one area where I know of challenges has been alcohol related, I suspect one glass of wine/beer is fine, but I wouldn't claim much beyond that, there again I am aware that BA has picked up the tab for more than that.