Sounds like to me you have a dead IAC valve, id just replace that and code 1 and 2 ( in listed order ) will go away, the battery issue thats very odd, i know of alot of volvo's that have 14.5 at high rpm's thats actually normall considering all the electrical componants that volvo put in there cars ive even seen some at 15, and the codes here on the site are alittle mixed up youll have to look at both sets of codes for the Fuel injection as i noticed one for the LH didnt have my code but the reg did and visa versa and i have the LH for sure, in fact i actually didnt even know that high voltage would thorw and error low voltage i can see but high never thought about it.