That this is a crap boiler, is clear. I've had it in my house for 6 years and it has been nothing but bother. To try and answer some of these:
The loud popping noise when you run water through it. This is the diverter valve starting to go. If the water is working fine then you can just ignore the noise. If the noise bothers you, then you should get the diverter valve changed.
The boiler coming on of its' own accord. The boiler has pre-heat so that when you run hot water the hot water comes in much more quickly. This means that it occasionally needs to pre-heat itself. How often depends on the ambient temperature. My one is mounted outside, so in the winter it's pre-heating maybe once an hour. God only knows how much gas it's wasting doing that.
All of the fault codes are listed in the manual. You can find the manual here http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&ved=0CEoQFjAC&url=http%3A%2F%2Fidealheating.com%2Fdownloads%2Fmanuals%2F202675.pdf&ei=df9jUvbBJ9Ob0AWykYHwBA&usg=AFQjCNE7oHA_jvyR1z-qxFIujd808I4xvw&bvm=bv.54934254,d.d2k
And to give you an idea, in 6 years of use I have gone through 2 PCBs, 1 diverter valve, 1 overheat thermistor and one hot water thermistor. This really is a truly awful example of British Engineering.
Hope this shelps
stephan
October 2013