Do We Control Over Sql Server Error Log Files ?

Hi, everybody
I am trying to run job that will
look for errors in error log files and save it to text file
In order to get up to last minute infromation I am using errorlog

1. at what point errorlog ranamed to errorlog1?
2. Can configurate size of errorlog file ?
3. Can I configurate time when errorlog ranamed to errorlog1

when i run in Sql Query analyser
print '------------ level 16 from last Sql errorlog file ----------------'
print 'These messages indicate errors that can be corrected by the user '
USE master
EXEC xp_cmdshell 'findstr /i /n /c:"level 16" InnvisionGMSSQL7LOGerrorlog.*'
go

I getting output
------------ level 16 from last Sql errorlog file ----------------
These messages indicate errors that can be corrected by the user

(0 row(s) affected)

when my job saves this command to file
I getting output
------------ level 16 from last Sql errorlog file ---------------- [SQLSTATE 01000]
These messages indicate errors that can be corrected by the user [SQLSTATE 01000]

How replace [SQLSTATE 01000] on user friendly message

Thanks