Re: Long Term Houseguests and rules.
It's easier on both you and them if you let them fix their own meals :) Cleaning up, you need to lead by example - guests pick up from what the hosts do. If you clean up and load the dishwasher after cooking, they will (hopefully) follow suit.
We had a Guest From Hell last year and he didn't follow suit in our cleanliness practices nor did he lift a finger. Because my husband's mother threw GFH out of her house, my husband tried to make up by keeping him at our house to prevent out right war between families but it was awful for me. If I suggested that he put his dirty dishes in the dish washer or pick up after himself, he would start talking how servants do everything in Pakistan.
Our GFH who was suppossed to stay 2 days ended up staying with us and the in-laws for 3 months! He was a free loader that didn't want to contribute. There's an urdu saying " Aik din ka mehmaan, dou din ka haivaan (?), aur teen din ka shaitan" Meaning if you are serving a person hand and foot, you can only do it for one day and after that they are a burden.