I guess there was no response because there is no way of giving you fixed answers - it depends.
The ETH sets out clear requirements for the EST Masters
, which I'm sure you have read through and checked against your own qualifications. There is a limited number of places, so the best get picked first.
ETH is a good university and there is high demand for its graduates but salary is not something that is openly talked about in Switzerland and you are in a specialised field, so maybe nobody knows. I'm sure you'll make a decent living.
Getting an internship without any German - I don't know. I guess you'll simply have to be a better candidate than the students who do speak German. Quite a few people on here have jobs without speaking German, so there must be internships without German being required. However, your English is not terribly good, so if you have neither excellent English, nor German, well, you'll just have to work even harder.