Hello my internet died. Again.
Mastitis, you also massage the duct/lump to help it pass, feed and hand express as needed. I don't know the stats on Mastitis, however a few people have had it just not always so severe. There are a few horror stories about it often it is caught early and sorted at least in my area. However we have great bf resources here which I am sure helps. I have never had it, I know of one lady who had it several times but still fed for a long time, oddly enough I see more thrush cases 
Hello Hawthers
Dream I wrote a fairly long post yesterday that went when my internet failed again. Sigh.
You are probably experiencing ligament pain general stretching, that ca be pretty painful
Anyway my best advice is to feed as much as you can in the first six hours as that really kick starts the milk making process and then as much as you can, I am sure you know this is great for your supply and once your mature milk is in that is when the feeding as much as possible really helps, if you can take the babies to bed for a few days that is often very useful.
However, saying all this twin pregnancies with their high level of hormones generally means twin mums have a great milk supply.
Breastpumps I am not hugely knowledgeable about, and hand expression is what we are supposed to promote now, especially as it can be just as effective if not more than a pump. I would perhaps see if any local groups hire double breast pumps?
I had physio yesterday afternoon and she said my joints and ligaments are not up to it. :( Can't really give me exercises as it will aggravate my spd. So I guess I a not going to be working much!