I just built my first wheel today, a front one. I followed the guide but still took me 2 goes (taking all spokes out again twice) to get it right, it's harder than it sounds. But if you take time to do it properly, afterwards it seems really easy. I now have it mezmerised in my head. It's quite fun too! Headsets are easy to fit, but would be better if you get it properly fitted. I'm sure your local bike shop would be happy to help for a few £. I managed to fit one of mine in before with a hammer and a blank of wood, just make sure you hammer it evenly. Bottom brackets are easy to fit, easily fit one in less than a minute providing you have the correct BB tool.