One of the enhancements that we made to Orders allows you to get access to Order Metrics without having to redo your implementations (CPQ etc). So you'd likely be able to take advantage without modifications to your homegrown CPQ integration. I could run you through the details there.
Regarding Expired status, yes, this has a special meaning in Zuora. It really means 'this subscription version is no longer the latest'. It does not really have to do with what the end dates of the subscription are and refers specifically to whether there's now a newer, more up-to-date version of the subscription. So I believe it'll serve your purposes well in this case. If you query for subscriptions with status not equal to Expired and term end date > 09/30/2017, your subscription with a 10/01/2017 end date should appear.
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