A tester is a sixpence. Grose, Dictionary of the Vulgar Tongue. Various editions, 1785 and later (mine is 1811).
Earlier (16th c.), the coin was worth a shilling (OED)

Fack is a variety of fake, in the sense of coiled. A Nautical word. When a sailor coiled a rope or hawser, he would lay the rope in fakes or facks. OED. My, that's quite a thwacker!
Also fake may mean to do damage to someone, but the meaning above is the one that applies. (OED)
A squib is a type of small firework, which "sparkles, bounces, stinks and vanishes." Grose, above cited Dictionary.

'White' was used as an adjective for all sorts of things; a white swelling was a bun in the oven, to put it in more modern slang, a wife who rousted her husband from the tavern was a white sergeant, and white tape was Geneva (gin).