1) look in V$SQLAREA for queries having a lot of buffer_gets, executions, and disk_reads. it will give you the most consuming requests in memory, those which were the most executed, and those which made the most disk accesses.

2) it knows, don't worry, and you won't even notice that a crash recovery occured if you do not look in alert.log file

3) - get a filesystem with some space (about 1Gb for Oracle itself, and the size you wish for data)
- change kernel memory settings, according to your OS and version of Oracle
- create group dba and user oracle
- get a X station
- click, click, click