I am a current volunteer. TEFL actually. Give me your info and we have a facebook group I can add you to.

As far as your questions go:

1. So I have school Monday to Friday and kind of overdid it with English clubs and now have about 3 to 4 a week. After that, I might have Armenian lessons or I go home and chill with my family. You will be tired from teaching though. I had never taught before and had no idea who exhausting it is. There are also side projects you'll do and you'll have some Peace Corps homework sometimes.
2. I would wait on the language. You might be given an opportunity this summer to do an online course. However, if you don't have time it's not a big deal. You'll go from zero during training anyway. Exposure to the alphabet might help but honestly the course probably stressed me out more than helping me actually learn much. If you do chose to study, study Eastern. Western Armenian is what the diaspora speaks around the world. They are slightly different.
3. Dating is something I don't personally do in Armenia. Partly because dating in this culture pretty much means marriage. You don't date a local unless there's a possibility for marriage in the future. Some people have made it work but not me. And dating other volunteers happens...no successful relationships yet however!
4. People ET mainly due to personal reasons I would say. We have had 2 ETs in my group thus far. Both were for personal reasons however. There was a very high ET rate a few years ago because people came for a program that ended up getting cancelled so they were here doing work that they didn't come here to do. For the most part, people will be medically separated which is a decision that PC makes if the volunteer won't be able to have a health issue dealt with in country.
5. Bring clothes that you're comfortable in. I thought I'd have to dress business casual all the time and that's not true. I wear jeans to school like the other teachers. Bring a couple nice outfits but don't overdo it. Also Yerevan has tons of shopping (a bit expensive however). You'll also be able to get things sent to you. A hot water bottle saved my life in the winter. Also just a regular water bottle is good. If you wear contacts, you can get solution in the pharmacies but it's a bit pricey. I have yet to find glasses cleaner so bring that if you wear glasses.
6. I don't know if I went through like this moment of culture shock. It's more like little snippets of it over time. You get used to things though. You'll fall into slumps. Your days will initially have tons of highs and lows and you'll feel like you're on a roller coaster but you learn to handle it. Your fellow PCV friends will help you immensely. There are some people here who I don't know what I'd do without.