Best is 10 everywhere. If that's too expensive, then 1 or 10 for log and 5 for data (and 10 for TempDB)

RAID 5 is terrible for logs because it has a high write overhead. Tran logs are write-heavy, not read-heavy.

RAID 0 for TempDB is a risk, if any drive fails then TempDB fails and SQL shuts down. Now sure, there's no important data in there, but TempDB is essential for SQL operation and if it's on RAID 0 and a drive fails, SQL can't be started until either that failed drive is replaced (which could be anything from minutes to weeks) or until someone figures out how to start SQL without TempDB and relocates TempDB to some other drive.