File Permission Questions

[AliKK]

Hello. I recently migrated my WP install (Genesis + Lifestyle) to a new server and new domain. All worked pretty well and you can follow my neurotic thinking and awesome help I got here: http://studiopress.com/support/showthread.php?t=37896

Anyway, one issue I'm having is with folders/files that WP wants to have access to to write over. These being mainly the /uploads/ folder, theme editor, adding/deleting plugins, and I fear, auto-upgrades.

On all my other WP installs on other servers, the default file/folder permissions have always worked. I assumed they would on this server, too. However, they aren't.

So, I asked the host and they recommended that I change the /uploads/ folder to 557, which does make the uploader work. I asked about that being secure and they said it's fine.

Two questions:

1. Is 557 for the /uploads/ folder okay?

2. Is there any reason why file permissions that should work end up not working after a server/domain name transfer? I checked my new install and by default, folders are 755 and files are 644, as they should be. These settings work on the old server but upon transferring, the same file permissions are not working.

So, yeah, any help is greatly appreciated!