I never read in this forum but was looking for info on Montessori and saw your post. This must be such a hard situation for you.
You sound very confident in your gut feeling that this is the wrong school for your dd, so I would definitely let go of that plan, regardless. Maybe you should look into the Tagesmutter option, where dd is at someones home with just a few kids. Usually someone can recommend someone trustworthy. Or look into 'Spielgruppe'. These are groups for 2-3 yo, getting quite common, they are smallscale and usually 'safer' than Kindies. Most of them are not daily, some are, in some it's your choice.
You sound pretty insecure about your German class. Why do you want to learn German in the first place, and why does it have to be expensive, and why can you only start every 6 month. There should be more options available, have you looked elsewhere.
I would tell the Kindie and everyone that you don't feel right with regular Kindie in general (I know that most Kindergartens have very bad safety by US standarts, by any standart, really, I've been down that path), look into the other options. Your dd, just turning 3 in Sept, would be one of the youngest anyway. If and when you find care you are comfortable with, maybe try and do something other than schooling for yourself to see whether that;s an issue or not.
And good luck!! I know how hard this is, and I've made the mistake of putting my dd through a hellish Kindie experience. Still feel awful about it. With dd#2, 2 weeks younger than yours, I will not repeat the mistake. 1 year in her life means everything while I just get put down for another year of procrastination. That I can deal with.