The NARA ADD free online databases have it all correct for those "collections" as to Home State New Hampshire. Now the one you cite has a note that 2 different codes for home states were used 2 different times when NARA transcribed. The code number 29 in NARA ADD record can be for New Hampshire or Missouri. Someone who transcribed the record for Ancestry made the mistake of transcribing Nevada which is code 28 and actually is for Nevada or Mississippi.
Since it is a problem with Ancestry you can click on "add alternate information" and correct it yourself and then also contact Ancestry through "help" to see if they can do any more, but I doubt it.
As for "Decoration" the ADD record has one record that has a line entry "Posthumous Decoration" and there is no code listed for this. According to ADD notes "Posthumous Decoration" would only have a code for the : "Air Force Cross, Army Distinguished Service Cross, Medal of Honor, Navy Cross". Looks like Ancestry means the box is blank or code not available. Not that there were no "Decorations" fiven. They should add posthumous as NARA has it but again I doubt they will change it. Just means he did not get any of the 4 listed by NARA after death.
As for 25th Inf and 27th Inf. At NARA one database has his " Major command, eg division or brigade": as the 25th and they have a "Regimental ROAD" that was the 27th. It also has it was the 2nd Battalion which Ancestry dies not include. Click on the ROAD for explanation notes for entry. As far a NARA is concerned this is not a mistake and Ancestry did not make a mistake in their transcription.
The NARA records do not need to be changed as I read the explanation notes, and basically can't be changed. Ancestry did transcribed it all correctly except for the home state of one record on NARA. That is the only one that can be corrected, if you are a mind too.
NARA ADD main webpage for online databases:
http://aad.archives.gov/aad/click on Vietnam War the search just first and last name as he is the only person with that name in those databases.