Can I have all my profile and saves on it and use it to play on other 360's? I want to also keep it there so I wont have to be moving it but have all my DLC on the hard drive. Can I do this? or do I have to load a profile from the harddrive when playing local multiplayer?

I don't really know what you're asking.

But...

You can totally move your harddrive to other Xbox's if you wanted to play a save of yours on a friend's Xbox. You can load your profile on someone elses' harddrive, but it's a 20 minute process.

Ok yeah I hate loading it through Xbox Live. Thats why I want to use a memory unit so that I can keep my profile and saves there. Then when I want to play in another 360 I wanted to know if I can load my proflle directly from the memory unit and not have to copy it.

You can take your game saves and profile so you can keep playing somewhere else, but for downloadable content make sure you are signed into live and it will also work.  I found this because my lil brother had to keep his RE 5 save on is memory card so he could come over and play co op with his own inventory.  He also keeps his gamertag on the memory card so he can take it wherever he goes so that works to and you just pick it from the dashboard, no hassle at all.