I hope you are trying to use the option

"Use current security context" which you fail if you are using a windows account. the best option is to use the...

If its going to be just your monitor server the a desktop level server would be fine. but assure to run without any load othe.

Can you post us the server spec. to me it looks like your server is hit in some hardware problem.

You can change to read only mode but not to stand by or recovery mode after a full restoration.

You will have to change the mode to 90 to have full features of SQL 2005 to be effective in your database.

Yes you can detach/attach the database. before that just confirm that there are no active enties in the log file else you need to go for the option of attach_log_rebuild_log.

Is your flog file full or dos it have reserved space in it?

check if you are able to coonect to the remote server from the client server machine. this could be a netwotrk/permission/firewall problem.

Reinstall the client tools in the server this problem will be solved.

Check for the article on data partitioning in the link given below.

http://www.sql-articles.com

IS xp_cmdshell enabled in your instance. If enabled check if you are able to ping the server and there is no network glitches.

Checkthe port number of the mirror port and the server name with correct tcp ip port.

Is the new operator a windows account user. OS error corresponds to permissionproblem either accessing the winows files or registry keys.

SP2 has fixed lot of bugs in SQL 2005. better you can go ahead without worrying of losing your logins and jobs. they are not affected.

Databases can be moved using the detach and attach method. For logins there is a script in MICROSOFT site that will script your logins with password. you can use that.