What would I use if I wanted to modify data based on results from other data?

I have two questions:

1. How would I go about filtering source data to exclude data from another dataset that comes from a different server and database?  For example something like: SELECT Server01TableOneID FROM Server01TableOne WHERE Server01TableOneID NOT IN (SELECT Server02Table01ID FROM Server02Table01);
2. What would be the best method to use if I wanted to change row data in a dataset based on data from queries performed on other databases?  For example: If fieldA in database01.Table01 = "yes" then set fieldZ in database02.TableX to "no"+ database01.Table01.fieldB

Here is how I am thinking to handle these:

Set up queries to get all the data that I want to work with in multiple datasets.  Then use a script component to modify the dataset I want to modify by querying the other datasets.

I'm not yet sure if this is the way to go or if there is a better way to go about doing these types of things?