Wells1, oh yes, I remember bitterly laughing at the cosy world of Penelope Leach - keeping your baby happy by letting him watch you peeling potatoes. If only it was that simple....
Here are some more thoughts to add to the list - worry if they are already duplicating others:
Don't beat yourself up about your son's lack of interest in rattles, mobiles etc. As far as I have seen, most newborn rattles are waved in futile desperation by the parent. My son's earliest toy was my scarf. Try giving your baby some interestingly-textured and brightly-coloured fabric to examine. This might buy you 5 minutes of peace.
To help encourage sleep at night, do get a bedtime rountine going now, even if nothing happens immediately. Bath, drink, etc. Do everything you can to make the ritual different to the day time activity, by your tone of voice, the lighting in the room, how you tidy things away, the way you move, how you say good night.
As others have said, hunger was, without doubt, the primary thing that prevented my sons sleeping when they were tiny babies. You say your son is big and chubby - do you think he has a huge appetite? I don't know if you are breast feeding or using formula but could you speak to your health worker about this? However, I bet you've done this time and time and time again.....
Also, take him out if at all possible, even if it's just round the corner to the local shop or for a look in the garden. Half an hour of fresh air or just a change of scenery definitely helped my two settle. If the weather is foul and there's nowhere to go, show him the insides of some kitchen cupboards or something, and then play with him. I found some extra activity/stimulation before the wind down routine to bed really, really helped. Even if it just kept them awake for a longer stretch in the late afternoon.
Someone said it might be that your son just doesn't like being a baby and will be more contented later. I think this is so true. My oldest son was the easiest, happiest baby round. As the years went by, he resisted every move that left his babyhood behind and became the toddler from hell. I just daren't tell you how late we said goodbye to some things! he loved being fed by spoon, loved wearing nappies, loved having his bottom wiped, loved his cot, loved being carried everywhere. At 7 years old and weighing in at well over 4 stone, he still asks me to carry him upstairs to bed - though he knows I can't.
My hair tearing out phase happened when he was a toddler!!
I hope things get easier for you soon. If you go down the maternity nurse/child carer route, and give yourself a few hours break, I hope it works out. Sounds like a very sane idea to me.