i.e. If after the photo has been sent to OneDrive will it stay there if I delete it on my phone (this is what I want to have happen).
third party photo sync apps don't work that reliably in my experience, onedrive is no exception. better to make use of icloud as it's near flawless. to answer your question, no, deleting a photo from your camera app/photo stream doesn't delete an uploaded photo
populism, the most important and misunderstood movement of our time
SheriffNZ: I do sometimes have to open the Onedrive app to trigger a sync.this.
I sync mine with google photos no issues.