Congratulations!!!
First, you need to talk to your pediatrician. Hold off on the cereal or any change in feeding habits until you talk to his doctor first.
You will notice that you will get a lot of unsolicited advice from well-meaning friends, family and even strangers. A previous poster is right... a lot of things have changed since we were babies, and a lot of advice is outdated. You have to take some of the advice, throw some out, listen to your pediatrician and then do what works best for you and your baby.
As far as the cereal goes... there is absolutely NO proof that feeding cereal will help a baby sleep. In fact, it's often the opposite. Often it causes tummy upset because their systems aren't developed enough to handle it, therefore causing gas and stomach aches, which of course hinders sleeping. The American Academy of Pediatrics (AAP) recommends delaying solids (including cereal) until 6 months because it can be a choking hazard, raise the risk of food allergies, and cause gastrointestinal upset. Some doctors will advise starting sooner for things like acid reflux or weight gain issues though, so talk to your ped.
As for sleeping through feedings... talk to his pediatrician about this too. My doctor told us that as long as our daughter is healthy, having enough wet & dirty diapers, growing & gaining weight then there is no need to wake her for feedings. At 5 weeks, it's still so early, and little babies sleep a LOT. So, try to enjoy it for now and get some much needed rest for yourself. You'll miss it later.
I'm sorry, I can't help with the period question. I didn't have a c-section... my period didn't return for 8 wonderful months. I hope you can be so lucky!
Good luck and try not to stress too much!