It is very common for a random person to come and hold your hand for long periods of time. This is especially true for men. It took my dad awhile to get used to random men coming and holding his hand.
Just bare with it.
A guest is always supposed to be fed. It is very rude if you do not eat the food offered to you. Fortunately since there is a famine you do not have to have seconds.
Once the people in Zimbabwe figure out what a picture is they love to have their picture taken. You must be stern to prevent them from hurting each other or you. Just say they can't get their picture taken if they don't listen to you.
Other wise it is a lot of fun seeing their faces.