The answer:
Ciao :-)
I'll try to answer a few of your questions:
Yes, the selection process is quite hard. My assessment day started with 22-25 people and at least 8-10 had to leave during the day. The rest was invited to stay for a final one-to-one interview, so it still doesn't mean that everybody got it.
English is not my mother tongue either. Like 'I just want to fly' said, there are lots of foreign crew and I would say their level of english varies from averagely good to fluent. As long as you are able to understand what people want of you and you can make yourself understood (which seems to be the way) you should be fine!
Glasses aren't a problem as long as you can see good with your glasses on. You will need a confirmation from your optician but they will let you know about this in due time.
I don't know about DTM or SFX base and if they need crew. But you could always start at a different base and then transfer as soon as possible.
Anyway, good luck with your application!
Any more questions let us know :-)
Arrivederci :-)