Hi there - the Powys Records Office can be checked out at
http://www.powys.gov.uk/index.php?id=647. (or just use
www.powys.gov.uk and go through from there). If you click on the section 'Our Records' on the right, in the next window you'll see Parish Registers for the different counties; click on eg Radnor and a list of available registers comes up. All these registers are stored on microfilm and I found it very helpful to figure out in advance which ones I wanted to look at. You do need to book a seat in advance as the space in the research room is very limited. The staff are very helpful.
The parish registers have records going back well before 1837, some to around 1600, but the early ones can be very difficult to read on microfilm. I found most of the late 18th/early 19th c. ones well set out and easy to read, though the ordering can be tricky between sections, and you need to keep a close eye on the list of dates & events in the registers that the staff lend you to navigate through them. Non-Conformist records are more of a problem, and the info is scanty.
The baptisms I wrote about are from the Llandewi Ystradenni register, so I don't know whether this would be St David's, which is the parish church according to a quick look on the internet, or St Harmon's. The church at Abbeycwmhir was undergoing repairs at the time which is maybe why they shifted it into the next parish. By the way, parish records for Abbeyc.h. are with Llanbister until 1831 (?) when the church at Abbey was finally recognised in its own right. The entries don't always say which church was used, but sometimes GOL is written with the person's name, indicating that they came from Abbey and were presumably 'done' in the church there.
Re the curiousfox entry - not sure - will look more closely. I'm no longer a member of the website there but if you want to pass the info on that I've posted, please feel free.
Good hunting!
Cherry