1) More detail on how direct NSA’s accesses are is coming, but in general, the reality is this: if an NSA, FBI, CIA, DIA, etc analyst has access to query raw SIGINT databases, they can enter and get results for anything they want. Phone number, email, user id, cell phone handset id (IMEI), and so on - it’s all the same. The restrictions against this are policy based, not technically based, and can change at any time. Additionally, audits are cursory, incomplete, and easily fooled by fake justifications. For at least GCHQ, the number of audited queries is only 5% of those performed.
2) NSA likes to use “domestic” as a weasel word here for a number of reasons. The reality is that due to the FISA Amendments Act and its section 702 authorities, Americans’ communications are collected and viewed on a daily basis on the certification of an analyst rather than a warrant. They excuse this as “incidental” collection, but at the end of the day, someone at NSA still has the content of your communications. Even in the event of “warranted” intercept, it’s important to understand the intelligence community doesn’t always deal with what you would consider a “real” warrant like a Police department would have to, the “warrant” is more of a templated form they fill out and send to a reliable judge with a rubber stamp.