1) The document provides information on various SQL functions for string manipulation, date functions, aggregate functions, and selecting rows from tables based on conditions.
2) String functions include concatenation, conversion between ASCII and character values, indexing and pattern matching. Date functions include adding/subtracting dates and retrieving date parts. Aggregate functions include average, count, max, min and sum.
3) Row selection can be done using comparison, range, list, string and logical operators to specify conditions in the WHERE clause. Distinct, TOP and PERCENT clauses can also be used for result set filtering.