I’m not sure whether this is the right website for this question – it is not technical – or maybe it is.
Can i upload a “placeholder” app to the appStore to grab a name i like and then update it once the “real” app is finished?
I wonder if iOS app names are unique?
and whether an update should be anyhow related to the original submission?
You can go to itunesconnect create a new appID, then create a new application based on the appID. You will have to upload a couple of blank images and some dummy text as required. It will then tell you if the name is available. If you get the name you have six months to upload a binary before the name is freed. If you need more time after that you can upload an incomplete binary, submit it, and then reject the binary. This can give you a more time.