HPFP failure in 335i / xi?

I am about to buy used BMW 3 series and I test drove couple of them , they were so nice , well engineered , tonnes of option & bottons, but what stopped me so far from buying it is repair & maintenance cost specially I heard Fuel pump doesn't seems to be very reliable , I checked car faxes and some of them were saying " Electronic Module reprogrammed " which I think that is some how is related to this problem but I am not sure if that fixes this problem or still is temporary solution ! is there any other point I have to be concern about to be known to go bad ? Also I heard on AWD models transfer case which applies power to front wheels like to start leaking , Is that true ? ( I am talking about US version BMWs )