I've just skimmed the thread, but wanted to send you my sympathies, very tough and HARD WORK it is having a small person running around.
There is LOTS of fantastic advise on this thread. I truly wish I had Mumsnet when my DS1 was around this age, he was incredibly challenging as a toddler and now at the age of 11, we often still have our 'moments' with him. One thing I do know from experience is that I have handled things very differently with my other two children (DS2 9, DD 8 months), I try as hard as I can to use the ignore the bad, distract technique. It's SOOOOOOO hard, but it really does work. Sadly, like the case often is, we did all our learning with our first born .
I think my overriding message is to try and create an environment where you are saying yes a lot of the time instead of no, it will help you relax a bit more and your DS will chill out too, they are SO switched on to your stress levels! So if at all poss, avoid situations cropping up, use anyway up cup, nappies, bring a snack box, strap in trolley, and distract distract distract!!
Good luck and stay strong/keep posting!!