This is a succulent. Most likely of genus Cotyledon. Perhaps others can correctly identify the species?
Almost all plants require air, light, water and the correct microbiology in the soil or growing media / potting mix to facilitate nutrient exchange - your new succulent most definitely falls into this category.
A larger pot will allow your plant to flourish. If kept in a tiny pot, your plant will modify its growth in order to survive - this will include smaller, slower growth and most likely no flowers.
I don’t understand what you mean by open terrarium, but that is not too important because your plant will thrive in any climate where the outdoor temperature does not drop below freezing. If it does, then you will need to keep your plant indoors during these periods, in any container that is free draining.
Growing a plant in a pot is very different to growing a plant in the ground. Plants in pots need a lot more care. However, you have chosen one of the easiest low maintenance plants to grow in a pot, so you should relax and understand the following...
- Generally, plants in pots have no connection to a larger ecosystem that would otherwise provide water and air and facilitate nutrient exchange;
- So, more often than we would if we were growing plants in soil in the ground, we must:
- water more often;
- add soil microbiology or nutrient more often;
- create a microclimate around the plant that allows it to thrive.
On this last point, a terrarium would be needed if the plant in question needed humidity and constant moisture. Your succulent requires a dry environment and irregular moisture.
Misting is great for plants that require high humidity and constant moisture. Your succulent requires a dry environment and irregular moisture and so will prefer water directly into the pot.
Depending on where you live and how much your local authorities treat your potable water supply, it might be best that you water this plant with water that has been boiled and allowed to cool to room temperature.
Growing media / potting mix - use a free draining media that allows immediate drainage and excellent air circulation. I find that commercially prepared bagged potting mixes designed to grow orchids in pots are excellent to use with succulents. If you don’t have access to that type of product, then you can make your own - use a blend of 50% small bark chips (5 - 10mm or 1/4 - 1/2 inch) and 25% compost and 25% tiny pebbles (5 - 6 mm or 1/4 inch diameter). Do not use soil from the ground.
Nutrient - succulents will survive with little to no nutrient added to their growing media. However do you want your plant to just survive, or do you want it to thrive? If you want your plant to thrive (grow well and flower) then you will need to add soil microbiology to your mix. This a is best done using worm castings from a worm farm, however I expect that as this is your first plant, you are unlikely to have a worm farm. A suitable substitute is any commercially prepared tonic that adds soil microbiology to the growing media. In Australia, we are able to purchase an excellent product made by Neutrog called “GoGo Juice”.
It is important to recognise that you can add unlimited nutrients (commercially prepared fertilisers), but without the necessary soil microbiology, these fertilisers will simply sour the growing media and kill your plant. Soil microbiology is the conduit between the plant’s root system and the nutrient in the growing media. Without it, there is nothing to facilitate the exchange between the plant roots and any nutrient in the media.
You asked a lot of questions and I think I’ve answered them all. If not, or if you have any other questions then please ask in the comments and I’ll update my answer.