1, Most of the stuff i read talks about 3 hrly feeds but DS seems to want feeding every hour or so and almost continuously every evening - is this normal? I really don't want to make myself sore by overfeeding you see so wondered if i should try and distract him a bit more. How long until the feeds start spacing out a bit do you think?
Every hour or so sounds quite normal for a newborn and lots of evening feeding is very common, it won't be like this forever! You need to feed him when he asks for it. As soon as you see him start to wriggle around and make sucking noises/faces he's ready to have milk. Every 3 hours is very structured for a baby, he has no concept of what an hour is so don't watch the clock, watch the baby. A minimum of 8 feeds in 24 hours is what you want to achieve and this would work out to every 3 hours but babies, esp. newborns don't tend to stick to a pattern like this. It's important to remember this is his drink as well as his food so frequent feeding is OK and normal and doesn't mean your milk is not good enough or isn't satisfying him.
2, Should i always offer just 1 breast each feed? Sometimes esp at night he is not satisfied with 1 but again i find offering both everytime is making me quite sore.
You should always offer the 2nd breast. He may take some, all or none but it's a good idea to offer it. Getting sore isn't good however. Are you using anything on your nipples? Lansinoh or vaseline for e.g? Some discomfort (notice discomfort and not pain) isn't unusual and doesn't necessarily mean your latch is bad. This discomfort should only occur at the beginning of a feed and shouldn't last the whole feed. If you're sore throughout the feed or are in pain with any damage then you should ask your midwife for some pointers on how to achieve a deeper latch. Off To The Best Start has some useful tips. Lots of mums experience some discomfort in the early days but this soon goes. How do your nipples look after he has finished feeding? Are they pretty much the same shape, perhaps a bit longer then normal, as when they went into his mouth or are they a bit pinched or lipstick shaped? Pinched or lippy shaped would indicate you're not quite achieving a deep enough latch and the baby is compressing your nipples on his hard palate- we need to avoid this. When you bring the baby to the breast make sure you hold his body in a straight line towards you, hold him nice and close and allow his head to move as he needs it to- best to hold his neck and shoulders not his head. Bring him to the breast with his nose towards the nipple and wait until you see him open his mouth really wide before swiftly moving him onto the breast. No point in trying to shove him on if his mouth isn't open wide enough. See the leaflet for more tips
3, Should i try expressing and if so what are the best times to do this? I started giving him a small amount of formula just before bed as he was so unsettled even after feeding all evening. Just 2 ounces and last night he only had 1 ounce. If i started expressing i thought this may help my supply and let me cut out the formula all together?
At this early stage the best thing you can do is to feed your baby directly from the breast as much as he asks for it, for as long as he asks for it and whenever you feel like it too (3 basic principles of demand or responsive feeding for you there 
). Expressing milk rather than feeding the baby won't help to up your supply, the baby is the expert at this so allowing him to feed often is going to be your best course of action. Any formula milk you give is likely to have a negative effect on your milk supply so is best avoided.
4, Finally - and so sorry for the long post roughly how long should a feed last? He seems to fall asleep on the boob you see and then when i take him off and put him down he wakes again as he has obviously not finished.
A breastfeed can happily last anything from 5 minutes to an hour per breast. However, if your baby consistently feeds for 5 minutes everytime or consistently feeds for an hour or more everytime then something is not quite right. What you need to do to know whether your baby has 'finished' (a breast is never completely empty- the constant production of milk means there is always some milk in there) is to look out for a sucking pattern with each feed: baby comes on the breast and his sucks are initially quite rapid- he is calling the milk from the breast. Once the milk has started to flow his sucks and swallows will become deeper and you probably be able to hear gulping. He will take pauses from time to time to have a rest and breathe (he's gotta breathe!) and gradually his sucks and swallows will become shallower (as the fluid content of the milk decreases and fat to fluid ration is increased). He's still actively feeding at this point even if he is taking pauses of 5 minutes of more. Towards the end of the breast the milk is very fat-rich and is quite creamy so he'll be taking little sips by this stage. His sucks will be almost like little flutters. If the breast feels soft and light and his fluttery sucking is infrequent (gaps of more than 7-10 minutes) then you can guess he's probably finished with that one and you can try gently lifting the breast away from him. If he lets go easily you can assume he was done and offer the one. If, however, he gobbles after it when you gently lift it you can assume he's still enjoying that breast and to leave him where he is. Once he's either let go spontaneously or you repeat the above and he does let go then you can offer the 2nd breast.
Hope I haven't waffled on too much