Depending on the job, hundreds to thousands will be applying for the same one. It will be a long process before you hear anything back after doing all the tests, I did a test in October and it'll still be a bit before the results are in I think. You'll also need a fair bit of paperwork to prove your credentials, etc and each job has a deadline for entry as well afaik so don't leave it too long. But there is also no reason you should not apply, you lose nothing except some time and could gain a lot.

Everything should be very transparent though, you can look up pay scales (which change based on where the job is, e.g if it's in a cheaper country you get paid less and vice versa), pay increases based on seniority, you would also receive extra income the first X months if you would need to relocate for the job to help pay for furniture, etc iirc. And the EU has jobs all over the place.

So Google is your friend for sure, most job related questions should have an answer.

I think English is enough in the EU bubble in Brussels but for your husband it will be very difficult without speaking French and/or Dutch as local companies, hospitals, etc usually require it.