What permissions (Profile) are required to run or schedule Batch Apex

Scheduled jobs run as "system", but I think there's still a user context, which means Date.today() or System.today() would be in CDT.

Update:

Just tested this and DateTime.now() returns GMT values.

Another update:

The docs say Date.today() returns the date in the current user's time zone. Based on the test below, the system knows who the user is, and it knows the user's time zone, so Date.today() would be the current date in the user's time zone. I confirmed this by setting my time zone to +10, and the system returned 2012-03-15 for the date.

// Brisbane +10 time zone
global void execute(SchedulableContext SC) {
  System.debug(DateTime.now()); // 2012-03-14 19:24:39
  System.debug(DateTime.now().formatLong()); // 3/15/2012 5:24:39 AM AEST
  System.debug(Date.today()); // 2012-03-15 00:00:00
  System.debug(UserInfo.getUserName()); // dev1@jeremyross.org
}

Good news - you don't need a visualforce page and controller. Bad news - you can't schedule jobs with 1 minute intervals. I think 5 mins is the minimum (but I'm not sure, you'd have to experiment with it).

How to run it (once) on demand? From Developer Console or Eclipse's "Execute Anonymous" block.

Make sure your user is added to debug logs and simply force running of the execute method you had to implement as part of the interface:

scheduledMerge sm = new scheduledMerge();
sm.execute(null);

Experiment with the cron expressions after you're satisfied that one run completes succesfully. If you're fine with frequency once a day - you don't need these expressions at all, go to Setup -> Develop -> Classes and click [Schedule Apex]. Only if you need multiple runs a day use code to schedule the class.

Last but not least - go to setup and type "Apex jobs" in the search. You should see info of all asynchronous tasks performed recently (scheduled jobs, batches, @future methods etc)