Rails AWS questions

I need to implement an API for my web app but i had some questions
before
diving into the code for it. I was hoping to get some help from you
experience individuals and rails rock stars.

  1. Is there a way to add authentication/login so api methods cant
    execute
    without proper credentials? Mainly, I want to be able to track activity
    from different people using the api and also want to keep out scriptors
    that
    might add bad content through my api. I think basecamp api has this,
    but
    i’m not sure how to implement.

  2. I have not yet updated to Rails 1.1 yet (i will soon), but does this
    change anything in regards to whether or not to use AWS? I saw Jamis’s
    article on respond_to stuff but i wasnt sure how it would work with an
    api
    call.

  3. I read the manual on ror.com about aws. however i’m having trouble
    deciding which dispatching approach to use. I want to use the one that
    fastest to implement but is also most flexible to soap, xmpl-rpc, rest
    clients.

Any help and insights would be greatly appreciated.