Congrats on your new baby boy. As other posters have said, it is normal for him to be feeding so much and falling asleep so easily and for you to be feeling so completely exhasuted so at least be reassured by that. I use KellyMom website for lots of advice on breastfeeding, it may be helpful to you in the coming months. It's US based but has great research and advice.
kellymom.com/
I have 3 DC and latest is still only a few months old so I feel your pain. My 1st DD wanted to suck a lot and was regularly unsettled in the evenings, starting around 4 or 5 pm and lasting for a good few hours. This got better with time (and experience on my part - getting to know her) but the constant need to suck was very, very tiring. I did keep feeding her (or letting her suck, I'm sure she wasn't truly getting milk all the time, just comforting herself - and that's completely normal) but what really helped with this was putting her in the soft Kari-Me sling we had borrowed. DH would take her in the sling and take her out for a walk for 45mins-1hr. Most babies have an unsettled time of the day, if you can, just succumb to it and remember that it does pass with time as they mature. Of course you can work around it too, go out for a walk with baby in the sling, or send out the DH with babe in sling for a good hour's walk while you have a bath and a rest. If DH can be out for longer, even better as it will give your baby a good long sleep as well.
With a jersey wrap sling you need to tie it quite tightly and securely, more so than you think, in order for the baby to be snug and secure in it and not start slipping down in it once you start walking. Babies have to get used to it too, and they may cry a bit at first but they usually get to like it quite quickly and cry in anticipation of getting tucked up in the sling and rocked off to sleep. I would really recommend a sling over a baby carrier (ie Baby Bjorn), especially for newborns as it's easier to put them in the frog and foetal positions that they remember so well from the womb. Try this website for a few ideas: www.littlepossums.co.uk/
My advice is to feed as frequently as you and baby want to. Baby only takes what he needs so he won't overfeed but don't let him go more than 3 hours between feeds until he has regained his birth weight and beyond. A good method for waking him is to cradle him in your hands and forearms and hold him out in front of you and wave him from left to right in a big swaying arc. It can take a while if he is very sleepy, so you do have to persevere. Do wake him for feeds because if he misses feeds he will lose too much weight too early, and your boobs can get very full and uncomfortable and you could get blocked ducts if you don't empty them regularly. He will grow into his own routine with time, and you will learn his sleep/eat pattern over the 1st few months. Saying that, babies change their habits regularly so what they're doing at 8 weeks won't necessarily be what they'll do at 12, 16 or 20 weeks. They will have growth spurts, every couple of weeks, or every couple of days even in the early days, they will seem to want to feed all the time. And then you will notice a day or so of long deep sleeps - that is the feed/sleep cycle and you can say Ahhh, i think that was a growth spurt!
Last tip - and this isn't for everyone - I swaddled my baby and would lie down next to her on our (firm) bed. No pillows or covers anywhere near of course, and we would breastfeed lying down. Once you can do it ok sitting up, and he is good at latching on, then you could try this as it means you can just get up quietly and leave him sleep, or scoot over and fall asleep yourself and he doesn't get woken by the transfer to the crib. KellyMom has advice on how to breastfeed lying down. What I do is I lie on my right side and get baby lying on her side facing my boob and then use my left arm up under her bum and back to shuffle her close to me and onto the boob. My right hand adjusts the latch if I need to and then once 'on' my right arm curves around her head and I lie on my upper arm as I feed her. At the very beginning I had to do the whole sitting-up-in-bed thing to feed and that's fair enough because they have to be latched on right but if you can practise lying down feeding as you get more confident, it is a lovely way to feed in the middle of the night or you can just do it for naps during the day. (Obvs co-sleeping isn't for everyone and you must read all the safety guidelines before doing so.)
'The No Cry Sleep Solution' by Elizabeth Pantley is is well worth reading as it is very sensible about how small babies sleep and is practical and humane about how to encourage good sleep habits:
www.amazon.co.uk/No-Cry-Sleep-Solution-Through-Foreword/dp/0071381392/ref=sr_1_1?s=books&ie=UTF8&qid=1352845626&sr=1-1&tag=mumsnet&ascsubtag=mnforum-21
Trust your own instincts, whether about feeding or sleeping or any of the other aspects that everyone has such opinions about - you will get to know your own baby! Good luck with it all and sorry for the over-long post.