A few queries at bottom
The commerce of Birkenhead was in all respects a branch of that of Liverpool, and chiefly devoted to coal, guano, and grain, - the quantity of coal alone exported being over one
million tons per annum. Many manufactories have sprung up within the last few years on the margin of the Great Float and other parts of the town, such as iron foundries, boiler-works, oilcake and seed mills, &e., some of the engineering works, shipbuilding yards, and forges being on a large scale. The Birkenhead Iron-works of Messrs Laird Brothers employ
from 3000 to 4000 men; these works, in connection with their shipbuilding yards, have turned out some of the largest iron-clad ships ; the engine-works, also belonging to the same firm, are on a very extensive scale. The Canada Works, belonging to Messrs Thomas Brassey and Co., click carry on an extensive business in marine engines, iron-bridge building,
pontoon and general railway work. There are also the Britannia Works (Messrs James Taylor and Co.) clicky for portable engines, marine engines, traction engines, steam cranes, &c. ; Messrs
Clay and Inman's Forge, for heavy shafting, &c.; the Wirral Foundry, for large engine castings, &c. ; and the Starbuck Car and Waggon Co.'s Works, for building tramway cars, &c. and Messrs Clover and Clayton's shipbuilding premises as well as other manufactories of less extent.

1 From what countries did they get the guano mainly and would it have been dangerous to store on ship or warehouse?
Guano (via Spanish, ultimately from the Quechua wanu, meaning 'dung') is the excrement (feces and urine) of seabirds, cave dwelling bats, and seals. Guano manure is an effective fertilizer due to its high levels of phosphorus and nitrogen and also its lack of odor. It was an important source of nitrates for gunpowder. Soil that is deficient in organic matter can be made more productive by addition of this manure.

2 Where was the Starbuck Car and Waggon Co.'s Works, for building tramway cars?
3 Any other works in Birkenhead (or Wirral) that would have been known worldwide mid 19th century

http://en.wikipedia.org/wiki/Starbuck_Car_and_Wagon_Company

I think guano mainly came from South America.

Although a little later than mid-century, Price's Candle works at Bromborough Pool and from the end of the century, the growth of Lever Bros. had gathered momentum.

http://books.google.co.uk/books?id=...0to%20britain%20from%20where&f=false

The 1875 Town Plan shows a 'Tramway Carriage Works' on the south side of Cleveland Street, between Vittoria St and Neptune St/Charles St. The buisness on this site is mainly scrap cars, spares, MOT's and repairs these days. I don't know where the site of Milnes & Voss were.

There was also the Vauxhall Iron Works in that area.

There was Seacombe Pottery

http://www.bbc.co.uk/arts/yourpaintings/paintings/seacombe-pottery-wirral-67766

Also Della Robbia Pottery made in BIrkenhead

http://www.studiopottery.com/cgi-bin/mp.cgi?item=75

Another was world famous Lee's Tapestry Works, although very late 19th(c)

http://www.bbc.co.uk/liverpool/voices/bhead.shtml

By the middle of the 19th century, Laird Brothers was famous worldwide for its skill in building iron ships.

So celebrated was the yard's expertise that it even made its way into one of the most popular novels ever written – Jules Verne’s 20,000 Leagues Under the Sea (1870).

In the book, the narrator, Pierre Aronnax, asks Captain Nemo how he constructed his super-submarine The Nautilus in secret.

Nemo says: ‘Each of its components, Dr Aronnax, was sent to me from a different point on the globe via a forwarding address.

‘Its keel was forged by Le Creusot, its propeller shaft by Penn and Co. of London, the iron plates for its hull by Laird’s of Liverpool, and its propeller by Scott & Co. of Glasgow.

‘Its tanks were constructed by Cail and Co. of Paris, its engine by Krupp of Prussia, its cutwater by the workshops at Motala in Sweden, its precision instruments by Hart Brothers of New York ...'

As we know, Jules Verne should have said Laird’s of Birkenhead. And, of course, the book is a work of fiction. But the fact that Verne chose our famous shipbuilding yard to help ‘build’ the Nautilus is testimony to how well-regarded Laird’s was at that time.