Right will try and answer questions I apologise if I miss any!
Best advice I can give is to get oneself to a BreastFeeding Group! You get to meet other new mums, they are informal, usually free, get expert on hand advice. Met some great and lasting friends at my local BF Group.
Cracked Nipples: Usually caused due to the baby not latching on correctly but some women do seem to have very sensitive skin. Rubbing breastmilk on to your nipples before and after a feed and letting them air dry can help.
Mastitis/blocked ducts: Make sure you bra fits properly and is not underwired. With Mastitis you really need to see a doctor but it's recommended that you continue to feed on the infected breast and to massage it in downward strokes to help clear the infection. A hot flannel on your boob can help and also expressing milk whilst under a hot shower or in the bath. It can be quite painful but it really does help clear the infection quickly.
It's so hard to do this in writing, much better face to face!
Here's some websites, the first one has video clips.
www.thebirthden.com/Newman.html
www.breastfeeding.nhs.uk/en/fe/toc.asp
www.breastfeed.scot.nhs.uk/BabyLed/index.html
Just to say, breastfeeding can be really difficult in the first few weeks as your uncomfortable from the birth, have a new baby and your hormones are everywhere. Try not to get too stressed as i've not met a woman yet who found breastfeeding easy from the word go. It takes practice but very quickly it becomes second nature and you become very adept at it! I personally never had any sore or cracked nipples, they did constantly leak however and I had blocked ducts on a few occasions. Either way just try it and remember there is alot of support out there and every woman is capable of breastfeeding.