Hi there! Congrats on your new baby!!
First of all,

, just 'cause! Breastfeeding is a learned process for mom and baby, don't forget. You are doing wonderfully, I'm sure. If you get really worried or frustrated, don't hesitate to see a lactation consultant. I could have saved myself some stress if I had seen one sooner!
Babies are often sleepy the first several days, especially if you had an epidural or other pain meds. Don't worry too much, but do try to wake babe as much as possible to feed. I've found that stripped down to only a diaper and constantly wipping a damp washcloth all over the face helps a lot. Do anything you can to stimule our babe -- tickle the feet, etc. Keep in mind the most babies lose a little weight at first (7-10% of birth weight) but should gain it back and be back where they started, at least, but the end of two weeks. The more you nurse, the quicker the engorgement will subside.
Why do you think your letdown is delayed? Often mamas don't feel their letdown for the first few weeks -- I don't think I started to feel mine until DS was about a month old. If you do truly have an issue with letdown, you can train your body to let the milk down with cues (think of Pavlov!).
There is GREAT information on breastfeeding on kellymom.com.
Go to
http://www.kellymom.com/bf/supply/letdown.html to learn more about slow letdown specifically.
Go to
http://www.kellymom.com/bf/concerns/...gorgement.html to learn about engorgement.
Hope this helps!