How to update SharePoint list columns including choice fields programmatically?

Question

Hi All,
I have a requirement to update multiple columns (which are choice columns) in a SharePoint list.  I'm a newbie at creating event receivers and timer jobs.  Not sure which one to do and where to start first.  There are approximately 4500
list items in the lists.  I was thinking I could use one list to maintain the Keywords and perform updates or timer job to any targeted lists. 
Scenario.  Anytime a power user of the sharepoint list wants to update any of the choice field items or possibly even the column name itself, they want to be able to make updates to any of the list
items or other
lists that contain the new name.  The columns I'm using are all choice fields named Assigned To, Division, Region, Job Title, Department, and Zone.
Here's sample code for Updating list:
 using     (SPSite oSPsite = new SPSite("team url/"))   
 using     (SPWeb oSPWeb = oSPsite.OpenWeb())         
 oSPWeb.AllowUnsafeUpdates =   true;          
 // get the List                
 SPList list = oSPWeb.Lists["Keywords"];        
 //Add a new item in the List                
 SPListItem itemToAdd = list.Items.Add();               
 itemToAdd["Title"] = "My Title Field";               
 itemToAdd["Assigned To"] = "Assigned To";               
 itemToAdd.Update();          
 // Get the Item ID               
 listItemId = itemToAdd.ID;          
 // Update the List item by ID                
 SPListItem itemToUpdate = list.GetItemById(listItemId);               
 itemToUpdate["Assigned To"] = "Assigned To Updated";               
 itemToUpdate.Update();          
 // Delete List item                
 SPListItem itemToDelete = list.GetItemById(listItemId);               
 itemToDelete.Delete();                   
 oSPWeb.AllowUnsafeUpdates =   false;         
Any help is greatly appreciated.  Please provide code sample and references.  Thanks!

Answer 1

Thanks Ramakrishna -- Here's what I have so far.
namespace MonitorChanges
        class MyTimerJob : SPJobDefinition
            public MyTimerJob()
                : base()
            public MyTimerJob(string sJobName, SPService service, SPServer server, SPJobLockType targetType)
                : base(sJobName, service, server, targetType)
            public MyTimerJob(string sJobName, SPWebApplication webApplication)
                : base(sJobName, webApplication, null, SPJobLockType.ContentDatabase)
                this.Title = "My Custom Timer Job";
            public override void Execute(Guid contentDbId)
                // Get the current site collection's content database           
                SPWebApplication webApplication = this.Parent as SPWebApplication;
                SPContentDatabase contentDb = webApplication.ContentDatabases[contentDbId];
                // Get a reference to the "ListTimerJob" list in the RootWeb of the first site collection in the content database           
                SPList Listjob = contentDb.Sites[0].RootWeb.Lists["ListTimerJob"];
                // Add a new list Item           
                SPListItem newList = Listjob.Items.Add();
                newList["Title"] = DateTime.Now.ToString();
                newList.Update();
Talibah C