The term 'Spook' refers to a type of electronic warfare craft, usually a Heavy Raider, that is primarily designed to trick DRADIS into thinking it is a Baseship or other capital ship in an attempt to draw fire away from the real vessels.
During the Battle above Scorpia the Cylons deployed three of these vessels in an attempt to trick the Battlestar Hermes into thinking there were six Baseships attacking instead of three. The Raptors from the Hermes saw through the trick however by using their peripheral scanners that revealed the deception.
Bloodsuckers refer to a tactic used by small groups of Cylon Raiders to hunt down enemy ships and disable their FTL drives with tactical nuclear weapons long enough for the main Cylon fleet to bring in reinforcements to finish the job.
The tactic was pioneered during the later stages of the First Cylon War and following the Fall of the Twelve Colonies the Cylons used it to sweep away any remnants of the Colonial Fleet. A typical group consists of 2 to 4 Raiders but on occasion just one 'Lone Wolf' Raider has been seen.
The Battlestar Hermes frequently encountered 'Bloodsuckers' during the months following the destruction of the Twelve Colonies. While they were sometimes successful in damaging the Battlestar these 'attacks' were in fact efforts by the Cylons to communicate with their agents aboard the Hermes. This tactic was also used by D'anna Biers aboard the Galactica in her effort to smuggle out the documentary she made about the crew of that ship.