Well, I asked this yesterday and never got an answer. Solved it myself eventually so i'll jus tout an answer here for completeness sake. If anyone else has a better idea, add that too.
For the first question:
-Write a cloud function in {Cloud code folder name}/cloud/main.js to parse xml.
-Write a background job in the same js file to call the function above.
-In your parse.com dashboard for the app, set the schedule details of the job under the Cloud code section.
For the second question:
Global variables can't be used in Parse.com cloud code. Instead store these variables in a Parse class (table) and access it from your client and/or cloud side.