You will definitely not need separate subwoofers, once you connect and set up your Oppo to the BL5s.
And you will be very satisfied with the phantom centre channel, once you set that up right (deselecting centre channel).
For movie playback, I would go with the 7.1 pre outs from the Oppo, to BL5 and BL3s.
Balance the audio level on the BL3s using the set-up on the Oppo.
Store a comfortable opening volume on the BL5s (see the manual). Use the Oppo set-up for multichannel to balance the channels - you'll get pink noise to separate channels, and they are all to be perceived to be at the same level from your listening position. If the volume adjust on the pre-out set-up doesn't let you get the BL5s to the right level, then adjust the start-up level for the BL5s correspondingly. It won't take you long to get them all balanced correctly.
Then it's down to how technical you want to get in your setup, when watching movies. I used the volume control for the receiver to adjust the volume up and down on the speakers. That is, I used the Beo4 to switch on the BL5s, and then used the receiver remote to control audio, etc.
Now, you can get an interface that will translate Beo4 signals to something the Oppo will understand, but I wouldn't bother.
Next - how to get your BeoSound 9000 into the fun, without having to change option settings?
BL5s auto-detect an S/PDIF signal, and you should consider how you want to use that. If your two-channel music playback will be from the Oppo, then you might want to consider sending the S/PDIF coax-out straight to the BL5s. But the BeoSound 9000 also has S/PDIF out, and everything that goes through it, is translated to that, I believe. (Can't remember off the top of my head whether radio, AUX, etc., is also sent through the S/PDIF).
If you have Powerlink from the BeoSound 9000 to the BL5s, and S/PDIF from the Oppo to the BL5s, and you set the BL5s up as if you're running a B&O components system - then, when you hit CD on the BS9000, you'll switch on the BL5s, and you'll be able to control their volume through the BS9000. But the moment you put music on the Oppo, what comes down the S/PDIF will take precedence - so you'll be controlling the BL5s through the BS9000, but the BL5s will assume the S/PDIF is coming from the BS9000, when it's coming from the Oppo.
You'll have to use two remotes.
I just switched Option settings from B&O to non-B&O when I wanted to watch movies. Then I controlled the BL5s for startup with the Beo4, put that aside, and ran the rest of the show with the receiver remote, with all speakers getting their signal from the pre-outs.
Make sure you have a sync-cable between the BL5s, that way, you'll be certain that both speakers are responding to the same command, and you won't have to worry about whether you have pointed the Beo4 so that both speakers "see" it.