Right, the generally accepted approach is to try and get readers hooked on a series with book one then they'll read through the rest. My approach is that if the first book doesn't sell or doesn't get good follow through, it's time to start a new series.
That said, I have rarely advertised later books in a series, usually at a launch, but my series all need to be read in order.
As for the pricing, I do discount the first book all the time, $.99 because I'm in KU. For the rest of that series, I price them at $2.99. I don't know about the UK, but in the land of the free and the home of the brave, $1.99 is kind of a no-man's land because you don't get the 70% royalty, and the book isn't cheap either. Best of luck.