1) These plans include the domain(in case that i want a custom domain)? Or i have to get one in another site?
We don't provide the domain, no -- you'll have to get one from another site.
1.1) In case that i have to get one, wich domain you recommend for a Django app?
All domain name providers should be equally good for a Django app. I can't recommend any one in particular (they're all pretty much the same) but we use Gandi and Joker for our own domains. A lot of our other customers use GoDaddy.
2) Can i pay this plans by year or its only monthly?
Absolutely, you can pay by the year if you like, and you get a discount (a year for the price of ten months). Just send us an email with the name of the account you'd like to upgrade, the plan you'd like, and your mailing address (for our tax records) and we can get that set up.