Ben,

There are a number of printed sources that you might find useful. Individual battles and combats are covered in Chaby and Soriano, often including details of losses incurred. If you have details / dates etc to help, some of the relevant volumes are available on google and are quite easy to search for snippets of interest.

Cláudio de Chaby, (1863-1882) Excerptos históricos e colecção de documentos relativos à guerra denominada da Península e às anteriores de 1801, e do Rossilhão e Catalunha, (Five volumes, Lisboa : Imprensa Nacional)
Simão José da Luz Soriano, Historia da Guerra Civil e do estabelecimento do governo parlamentar em Portugal: comprehendendo a historia diplomatica, militar e politica d'este reino desde 1777 até 1834, (Nineteen Volumes, Lisboa: Imprensa Nacional, 1866-1890)

João Torres Centeno
O exército português na guerra peninsular, Volume 1, do Rossilhão ao fim da segunda invasão francesa 1807-1810, (Lisboa : Prefácio, 2008)
O Exército Aliado Anglo-Português, 1809-1814, (Lisboa : Tribuna da História, 2011)
Auxilio britânico e preparação do exército anglo-português, in O Exército Português e as Comemorações dos 200 Anos da Guerra Peninsular, Vol. III (2010-2011), pp. 51-74
Given the increasingly important contribution of Portuguese troops in the extensive range of allied army operations post 1810, we all live in the hope that João will research and publish subsequent volumes to accompany his seminal book on the period 1807 to 1810.

You will no doubt already have viewed Challis and Hall.
Challis, Captain Lionel S. British Officers Serving in the Portuguese Army, 1809-1814
Hall, John A. The Biographical Dictionary of British Officers Killed and Wounded, 1808-1814, A History of the Peninsular War, Volume VIII; London: Greenhill Books

I have not yet viewed but believe the following to be, perhaps, even more enlightening than Challis. As you can see, they were researched and (the final instalment) published around the same time as Chalis' article but have perhaps not been so frequently referred to given they're in Portuguese and difficult to procure.
Col. Henrique de Campos Ferreira Lima, Relação dos oficiais ingleses que serviram no Exército Português durante a Guerra Península in Boletim do Arquivo Histórico Militar, vol. XV - 1945; vol. XVI - 1946; vol. XVII - 1947, vol. XVIII - 1948; vol. XIX - 1949. These are on my "must have" list.

Grehan's article in this book may prove useful for background:
John Grehan, ‘Wellington’s fighting cocks: the Portuguese army in the Peninsula’, in Ian Fletcher, (ed.), The Peninsular War: aspects of the struggle for the Iberian Peninsula, (Staplehurst : Spellmount, 1998)

If you do not have already, I can highly recommend the following for context:
Benjam D’Urban, The Peninsular War Journal of Major General Sir Benjamin D’Urban, 1808-1817, (London : Greenhill Reprint, 1988)

Whilst not directly relevant to Batalhão No. 5, you will find some very useful contextual material for British officers in Portuguese service to complement the sources Bob Burnham has pointed you to in:

F. C. Carr-Gomm (ed.), Letters and Journals of Field Marshal Sir Maynard Gomm, (London : John Murray, 1881)
Sir William Warre, Letters from the Peninsula, 1808-1812, (London : John Murray, 1909)

Both are available online.
Best wishes
A