Oracle Database Discussions

Hi,
iam student and learning oracle .Iam beginner and goggle a lot on database refresh ...........i have some queries related to it .

1) only there are 2 methods of refreshing a dtabase that is though rman incremental bkp /hot backup and exp/imp/datapump is there any other alternative method apart from this ......

2) if iam using rman should i drop the existing database and duplicate ie clone a fresh one and do i only require incremental level 1 backup....

3) i have created asm instance manually and we always connect as sqlplus / as sysdba . i tried it connecting though username and password and for that i had created a passowrd file and done the enteries in tnsnames.ora file
but couldn't get connected that way so is it that i can't connect as username/password

hey gurus please help me in this to understand

Thanks