These signs are used over here only for unskilled labor, holiday jobs etc, especially in restaurants or shopping malls, usually in jobs requiring qualification you are expected either to make speculative application or react on official vacancies like offered at the employment agency or on the companie's website.

That really depends on the kind of job. But right now it's the easiest as it was for ages to find a job, especially if you have a completed Dual education so you can apply for the jobs requiring (your) qualification. Especially employers looking for qualified staff require you to have such a completed training and often specifically mention the official job title they request you to have. Unemployment here is 5.6 %, which is near the absolute record low since the reunification of my country. Ten years ago, situation was often desperate. Of all my colleagues during the dual education, so roughly 60 in my dual education, afaik a good handful could stay in the job. By now people in my profession are desperately wanted and this will continue for a while as people retiring can't be replaced fast enough and due to the very specific job I do (working for a public authority), they can't really lower the standards.

Minimum wage is € 8.84 per hour - dear waiters / waitresses, if you realize Germans gave you a really stingy tip, some of them forget or never realized you depend on the minimum wages far more than over here.

Yes, I would. If you can imagine working for an authority it's a good idea.