#1 is true whether or not #2 is true, because there is no adversarial process in the FISA courts. A one-sided legal process is never a meaningful check. With regular courts, even when the
initial process is similarly one-sided (as it is with search and arrest warrants), the fact that the outcome
will be subject to adversarial process down the road is something of a constraint (but, even then, I don't think anyone is going to be point to the regular warrant process as a particularly
strong check on executive power.)
The FISA warrant process, because of its secrecy and because it is generally not subject to downstream adversarial process, isn't a meaningful check. If the judges on the FISA Court are extremely diligent, it might be better than nothing, but given the secrecy around it, its unlikely that anyone not directly involved will ever really know whether or not it is (which is one of the things that makes it less likely that it will be.)