Are foster parents still automatically surrogate parents for purposes of IEP Team and consents? Is it the SAU's responsibility to seek out legal documentation of parent status?
Yes, foster parents are still automatically considered surrogate parents if they agree and have the capacity to serve (see Appendix I MUSER 34 CFR §300.519). You are not required to seek out legal documentation, but it is a good idea.
How do you find out if a "biological parent's" rights are terminated?
Contact the local DHHS office.