William McFarland or McFarlane : Short Biography

Researching my GGGgrandparents - William McFarland and Catharine Murray. 

I'm running into a lot of brick walls trying to trace my ancestors to Ireland - and looking for any suggestions!

William is son of Andrew McFarland and Catherine Murrey. He was born in 1818 and I believe it was in County Tyrone.

Catherine is daughter of Charles Murray and Jane ?, believed born in Donegal in 1818.  I have no more information on this line, other than census says she came to New Brunswick Canada in 1824 or 1825.

William and Catherine were married in New Brunswick in 1842.

William has at least two brothers - King (1811) and Andrew (1815).  I've seen online reference that they were born in County Derry, but there was no documentation.

These brothers and their families came to New Brunswick, Canada in 1833 (or maybe 1832)

I have seen that Andrew's parents were either John and Mary Ann McFarlane or Armour and Rebecca McFarlane - looking for documents to prve which one. 

A John was born in 1715 in Liscabble and married Martha Armou of Lignabraid, Ardstraw. 

Have also seen a list of Leardon (near Gortin) McFarland burials - but not sure how (or if) they are tied to my line. 

I would appreciate any help and suggestions of places to hunt next.  Would love to have a townland before traveling to northern Ireland this summer!