The bit re stronghold is I'm afraid now rather queried - it comes from a theory held by Dr Oliver in the mid 19th century - that however there was in all probability a small keeill is agreed - many of the crosses in Braddan yard were taken there from surrounding areass in late 19th century and it is not clear that they were actually local to site

the bits you mention are illustrated on my page http://www.ee.surrey.ac.uk/Contrib/manx/parishes/bn/braddan.htm