Structuring network for cloud storage

[thenatural]

Can someone help guide me to more resources, etc for learning about how to structure a network for cloud storage? I have a startup and a key feature we're offering is cheap cloud storage for subscribed clients. I was tempted to use Amazon instead, but I think our own means a better experience for our clients (assuming it runs well).

We're on a fiber ISP with speed options from 10/2 to 100/20, to give you an idea of what our connection looks like. We don't yet have any clients for cloud storage, but we're talking to several and I want to be ready for when we do.

Overview:
- Clients have 1-4TB to backup (initially they'll send us data via HDD, then new stuff will be backed up over the web)
- Clients each have a Synology NAS (varying size and model)

Specific questions:
- How best to structure so that when client uploads overlap we can handle it
- How to know how many clients we can have on a single IP

I have other Synology specific questions (such as do we need to virtualize, etc), but those aren't for this forum.