Yep, you have a hell of a job ahead of you.
Sounds like you have the right idea though. Luckily we're in an AWS world and you can implement this kind of system on a reasonable budget in an integrated ecosystem.
Generally you want to gather your mezzanine files in an S3 bucket, determine your encoding profile, and use something like an Elemental Cloud cluster to generate your renditions.
I've never used ZeroMQ, but also take a look at Aspera and SQS to see if they fit in your price range. I'll admit I've seen bottlenecking issues in both, but these were amidst cutting real-time highlights during a full slate of hockey games during our NHL.tv launch.
In terms of considerations:
1) If you're only using DASH, consider your video player, especially for Apple devices. 2) Choose your transcode profile wisely. The less renditions, the less overhead. 3) Troubleshooting DRM is a bitch.
Gotchas:
1) Consider your content metadata workflow. If you're associating things like titles and descriptions with these videos, you'll have to have a separate system in place. The industry standard is thru MRSS feed. 2) S3 is your best friend. If you're setting up any automated workflow, remember that, and trend towards using watch folders and 0 byte delivery.complete files as markers for triggering workflow. 3) Cost will escalate if you're storing mezz files, consider the best archival practice for your situation (S3? Glacier?)
Good luck!