They were grown this year, they are about 3 months old, they will be around 1 to 2 inches tall, you will have to plant in pots and get them started before moving them to where you want, large pots or outdoors, if you live in a warm climate. These do really good in pots when taken care of in about 4 years you will see fruit
I would plant in smaller pots first because they are small and then as they grow add them to larger pots. Yes they do extremely well in pots, that is how mine is kept, they stay indoor all winter and sits on the patio during the summer. They bear fruit indoors and out. No just some sun light from a window does well with them
I tell people to go to google and type in how to grow tangerine trees from seeds and they give the best information there is. I also have the ones getting the small trees to do the same because they tell you what to do best.