1) Backup schedule is determined by the length of retention time purchased by the customer. If they want 4 weeks of retention time, we do a synthetic full every 14 days, and keep 3 backup sets. This takes more storage, but ensures we can go back 4 weeks. We always under promsie and over deliver. Incrementals are the same - it's an option that a customer can pay for. Most customers get 1 incremental a night, but others get incrementals every 1 hour.
2) We store them on a few different devices. External USB drives are the most popular due to cost - but they end up causing more issues than they are worth. We actually contacted the same vendor who makes the Zenith NAS, and get our own white box NAS. It comes with a few drives in a RAID 5, a few GB of RAM, Gbps NIC, and Storage Server 2003. We install VMWare server, and can spin up VMs on it in the event of a local server failure. We've already had to do this for 2 customers, and it saved us and them HOURS / DAYS of restoration time. They are now customers for life.
3). We replicate offiste to our datacenter with pretty good success. We had a few issues, but Kaseya support was (eventually) able to help us get all of them resolved. The dashboard makes it pretty easy to manage and keep up with any issues that do come up. We have also tested spinning up a customer server as a VM on our ESX cluster, and that worked well too. Really helps us provide a complete DR solution for our customers. We are replicating between customer sites in a few situations - and it works just like it does to our colocation facility.
Getting all of this to work like this wasn't as easy as it should have been ... but now that it's up and working we love it. We're migrating 1 or 2 clients a week from our previous backup product (Vembu) and so far everyone likes Kaseya BUDR WAYYY better than Vembu or NovaStor that we've used in the past.