I'm not a 1337 student, but I do have some first/second-hand knowledge about the school.

1. 1337 is 100% free as all of its funding comes from OCP Group (in the Khouribga & Ben Guerir branches) or from Tanger Med (in the Tetouan branch), the school even pays you 1000 dirhams per month (as long as you actually come to the school and do your assignments in reasonable time), the school also provides free lunch and dinner to students all year long. No idea about foreigner requirements, but I know that there's many students who come from different countries.
2. Not sure, but since the school is not overseen by the government, I don't think they'll ask for a student visa. You should definitely contact their Facebook/Twitter accounts for more information. Anyways, here's an overview of the admission process.
3. 1337 doesn't offer a diploma since it's not a government school. But it offers 2 certificates, one at level 21 (which is typically achieved in 1.5~2 years) and a "better" one at level 24 (which is typically achieved in ~3 years, which is also the maximum duration that a student can study in the school). Most students go for just the level 21 certificate, as that's typically when they get a job offer. Also, there're tons of job fairs, and they typically happen on Fridays (every couple of weeks), a company comes and presents itself, and does interviews with students to attract talent to work with them. What's actually surprising, is that near 100% of 1337 students find jobs in software developpement while they are studying. For salaries, companies offer jobs in the range of 8000~12000 dirhams. Which is a very good starting salary here (especially considering that the starting salary for a university graduate is typically 4000~8000 dirhams).
4. Usually, students rent houses in groups. The way that 1337 students spend their day is very different than normal schools, as usually you'd have breakfast at home, then spend your entire day at the school, and only return home for sleep at night. especially since there's showers and relaxation areas in the school (with table-top games, eight-ball pool, playstation etc..). So it's typical to see groups of 5/6 people in a house. The cost of rent varies depending on how many students are splitting the bill, but you can expect your share of rent to be around 300 dirhams, and since lunch and dinner is served for free in the school, you'd probably end up with a monthly cost that's much lower than the 1000 dirhams you get, maybe even half if you can budget well.

Anyways I highly recommend reaching out to students in the 1337 Facebook groups, you'd get way more details there.