The Wanganui Heritage library has been a godsend with information on part of my family. This library is very well organised with a wonderful up-to-date film reader which was donated to them. Their biographical card index means that a walk-in researcher can get to the right data quickly.
They are not up-to-date digitally, nor is their photograph collection, I've no doubt they have one, but its well hidden. You can contact them by email but again, its not a strong point with them and in this way, they are behind the times which can be frustrating. A physical visit is your best bet or send a letter. Their research cost is reasonable. 8 out of 10.
Wanganui also has a local museum, again, not up to date in modern methods of communication, expect frustration either by email or by a visit. Snail mail they know and it might work more consistently. 7 out of 10.
Wanganui has two cemeteries, Head Rd and Aramoho. Head Rd is right in town and is closed for burials. Aramoho is a large cemetery a 15 - 20 minute drive, less if you know where you are going! The New Zealand society of Genealogists have the index which is part of the cemeteries index on fiche and available at most large libraries. The Aramoho cemetery is contactable by email for lookups but the index is not online.