I've been reading about SuiteAnalytics Connect and found conflicting reports on performance. If we use SAC can we do data refreshes as much as we want? (Like once per hour) Or are we limited to just once per night Also can we just update on DELTA, like just what has changed since it last ran? Not sync everything every time?

Unfortunately, not really. If you want a pre-built DW for NetSuite that already pulls only incremental data (using a connector that runs on front-end searches), check out www.satorireporting.com

In terms of performance, SuiteAnalytics Connect is best for large scale data extraction for example for data warehousing. If you try using it for real-time reports the performance will be subpar, but for simple queries with a large number of results, it's hands down the fastest integration method available.