1. You can issue the db2level command.
2. You can issue the following select statements to get various pieces of information (I beleive that 8.2 FP9 is required to issue these, but I don't recall exactly when they were introduced). They are defined as UDF's in your database.
SELECT * FROM TABLE(SYSPROC.ENV_GET_INST_INFO()) AS SYSTEMINFO;
SELECT * FROM TABLE(SYSPROC.ENV_GET_PROD_INFO()) AS SYSTEMINFO;
SELECT * FROM TABLE(SYSPROC.ENV_GET_SYS_INFO()) AS SYSTEMINFO;
Look at the output of these and then select only the columns you want returned.