I am using wcc184.108.40.206, is there any method to export/import workflow definition from staging to prod? since in my prod env, revising workflow manually from ucm admin console is prohibited, we have to use a tool/script to import workflow definition from staging env.
Another question is if we use bpel as integrated workflow engine, can reviewer use ucm console(from "my content server"->"my workflow assignments") to check workflow info or take approve/reject action?
Ad #2) not OOTB. All 'workflow' pages work with native UCM workflows and call their related services. If you use BPEL Component (see http://docs.oracle.com/cd/E28280_01/doc.1111/e26692/append_bpel.htm#WCCSA1250) and pass workflow processing to a BPEL PM instantiated workflow from a native UCM workflow, the native workflow might still be not completed - it should leave the item in the 'Review' status.
is there a link in BPM worklist for him/her to open doc info page in ucm console for reviewing metadata and further more checkin a new release?
This very much depends on which BPM worklist you mean. And even which product (license).
I have to admit it might look a bit confusing, but if we focus on two license SKU WebCenter Content (formerly, Enterprise Management Suite), and WebCenter Universal Content Management (formerly, just UCM) we may find that:
BPEL PM is just a back-end workflow processing engine. I think it contains some GUI OOTB, but it is mainly for administration, and all user-facing screens are created as a part of the process. If there is a standard component for a worklist I am more than certain that it is completely ignorant about UCM, but on the other hand, you should be able to write your own, which may call UCM's (web) services.
With BPM Suite it used to be the same, only quite recently, BPM Human Tasks were enhanced by an option to add a document attachment to a a workflow (see http://jvzoggel.wordpress.com/2013/01/22/using-attachment-documents-with-oracle-bpm-human-tasks/). From what I have seen so far, however, this does not seem to be related to UCM workflows. In fact, when I tried to create a 'BPM Suite' workflow and start it from BPEL Component, it didn't work (someone then explained me that my workflow did not contain something called a composite which is mandatory for the compoment).
From what I write it is also obvious that I am not exactly an expert of finesses of BPEL/BPM. Yet, I think the conclusion is that you will have to write process's front-end yourself, and then, you should be able to manipulate with metadata, create new revisions, etc. Note that it kind of makes sense, because in workflows, it might be desirable to fill-in this metadata and this step, and that metadata in that step (btw. one thing that is quite challenging in native workflows).