I have to place about 200 images into a Layout in Indesign, most images need to be cropped. Is there any disadvantage if I don't crop the images first in Photoshop? The Layout is for a book design which will be printed offset.
Not really. In fact, there is an advantage by not doing so which is you can reframe in InDesign and have room for playing with them.
But if your images need a "mechanical" crop, for example, all were well taken and framed correctly, but you need a square proportion, you can benefit for some automatization, like a Ps action.
In the old days where you could send the base files (Indesign) and you were limited by space, yes, the "norm" was to crop and resize before so you sent smaller files.
But normally these days you send a PDF that automatically crops and resample the images (and the bandwidth is enough where you do not really need to save space)