I have found that teacup piglets can be weaned at 4 weeks old if they have been started well on pig pellets. These piggies will reach their final adult size between 2 and 3 years of age. They will generally weigh 40 to 65 pounds. I have read however that some of these small guys are only 15 lbs as adults. My smallest teacup adults are between 35 and 40 lbs. One sow is around 55 lbs. My male is 1/2 Juliana and 1/2 pot belly and he was 20# at one year old. They are quite easy to maintain and may live from 15 to 20 years.
Socialization ... the following link might be helpful so you can teach your pig to do the things you would like.
Pine shavings or pellets are good to use for litter. When you start litter training, your pig will most likely use the bathroom in places other than the litter box. If so, move his droppings to the litter box and show him where it is at. You shouldn't clean all of his mess from the box every day. By leaving a few droppings inside the litter box, this teaches piggy that this is where the bathroom duties are to take place.
The more you guide the pig to the box, the better. Moving him there every so often reminds him of his bathroom's location and the scent will probably stimulate his urge to use it. With each time he uses the box, it makes him a little more likely to use it again in the future.
If you keep your pig outside, you should provide it with some sort of shelter like a doghouse. These pigs love blankets or towels in their beds. I have even given them old pillows. They do not like the cold very well and they will use the blanket to keep warm. If there is room in your back yard it is nice to give your pig something like a baby pool to lay in when the weather is hot. Small pigs such as these can sleep indoors, outdoors, or both.
In the winter, I keep the pregnant sows in the house in big pet kennels by the back door. I can easily let them out to do their duties on the patio and then keep it swept off. All of the others get to stay in a 8 by 12 foot little wooden barn. Lots of straw on the floor is great as they love to burrow in it. A heat lamp is nice too as it really helps take the chill off if you have the barn fixed so drafts can not blow in. I leave the door open just enough to allow them to go in and out. I have used a large piece of heavy fabric to hang over the door where it is open and they simply push their way in and out such as a doggie door would work.
Feed your pet appropriately for they can gain weight unnecessarily. Pigs constantly think they are hungry because they do not have a thalamus. Overfeeding can be very dangerous and even cause premature death. These guys do not require much food. When you first get your pet, if it is a baby, you only need to give it 1/4 cup of pig pellets both morning and evening. In between that you can give them fruits and vegetables while you are working with them or training them.
Pigs should never be given Avocado or Chocolate which are poisonous to them. Pigs should not be fed salted items such as potatoe chips or salted popcorn. Air popped corn is fine every once in a while. Cheese and meats are also no nos. Vegetables should represent 25% of their daily diet and ideally consist of cucumbers, limited amount of potatoes, celery, peppers and some green vegetables. Fruits should always be given in moderation because of the natural sugars. (Pearls Before Swine) They enjoy watermelon that has some fruit left on the rind. Depending on how active your pig is, will determine how much feed it is given when it is an adult. Follow the directions on the back of your feed bag.