PgBackrest questions

Hi,

I am testing Pgbackrest and I have few questions.

please help if any one has tested these cases.

1. I used postures user to perform backups and restores with Pgbackrest
tool.
The Trust authentication in pg_hba.conf file is working without issues.

If I use md5 authentication in pg_hba_conf file and postgres user password
.pgpass file, the pgbackrest backup is failing.
Where should i need to mention the password for postgres user in order to
success the Pgbackrest backups?.

2. All the restores through the backrest is going to refer the Wal
archive files under archive/<stanza name>/* directory, which are taken from
pgbackrest?

3. What is the compression level by default in pgbackrest?

Thanks,
Chiranjeevi