Looks like you are dizzy from all of this information and I understand how you feel!
Let me explain a little bit:
You will get a detail explanation of the HUD-1 with a line-by-line from the title company. Also, you should have received a initial good faith estimate from your lender which can not be more than 10% of the final HUD-1. For most of the title companies if the difference is over $1,000 they will ask for cashier's check. Furthermore, if there are any additional changes during the settlement and it affects the final HUD-1 the title company will cut a check and give you the difference. However, that is only if you have credit, if it is the other way around you can give a personal check.
Best all luck and Congratulation!
There are might be additional fees for services that were ordered by you, if not paid prior to the settlement.
Your buyer agent - if you are working with one - should be able to answer all these questions for you.
Plus the fees on your final HUD can't exceed what you were quoted on your initial Good Faith Estimate by a more than a certain percentage so no need to worry. You may be off a few dollars here and there and that is usually due to a variance in daily interest, final homeowner's insurance premium, title/recording fees, etc.
I have rarely seen these checks used, recently, but the idea is to keep settlement from being held up over a minor amount of money.
A good Realtor will review the HUD-1 for you prior to settlement and minimize these adjustments and overlooked charges.