IPRs_to_OW2

Does an organization submitting a project to OW2 have to transfer its IPRs to OW2 or can IPRs stay with the organization?

There is no obligation to transfer any kind of IPR to OW2. OW2 is very liberal in this respect. In case a project, for any reason, wants to transfer an IPR to OW2, this is possible. Being a legal entity, OW2 can take over an IPR when necessary or required by a project. In case there is a CLA, the CLA is signed between the contributor and the project lead, not OW2.