C. .cfr files may be invoked directly, unless that functionality has been disabled.
A2:
B, C, D, E. Queries may be passed to the query attribute, and all simple data types (including dates, numbers, and strings) may be passed as input parameters.
A3:
A, B and D. C and E are not supported at this time.
A4:
A, B, C. All of these return queries (they are not database queries, but any query object is usable), the other three do not return queries.