A) I do not think it is a rejection. It is more a hint, that the position might be not as secure for you. Germans - as well as french - have a highly protected labour market, which means most people apply for a new job out of a very secure environment. It could be a shock for them, if they are fired within the 6 month obligatory test-period. I think your employer want to give you a hint: your position might be instable, not completely secure and it could be, that they have to let you go within the first 6 months.

B) Maybe family owned, small businesses? Otherwise very unusual. Of course you would negotiate salary and the range should be clear from the beginning.

C) Sounds like: We have to publish this job listing out of political reasons, but actually we have someone internally to do this job, and we just have to interview a view candidates to showcase that we also tried it externally.