"FYI, re: 3 million. LFL was very clear to us that no fixed number of total clones would or could be assigned. Therefore, the number 3 million (plus) does not represent the entire fighting force."
— Ryan Kaufman, TFN Lit boards.
[2]
While the Wizards of the Coast Roleplaying Game statistics list a Venator as only carrying 2,000 troops this is superseded by the source material. The Revenge of the Sith novel received line item edit approval from George Lucas, giving it a quasi G level canon ranking and consequently higher standing. Further, it is notable that many of the published statistics for Revenge of the Sith craft deviate from other published sources (e.g. Labyrinth of Evil, Revenge of the Sith Incredible Cross Sections). This is no doubt due to game mechanics, and is entirely unsurprising, as the first charge of Wizards of the Coast employees is to make their games fun and engaging, not to maintain continuity.
[3]
A Trade Federation ship is credited with being able to haul 5 million+ tons in The Star Wars Roleplaying Game Revised Core Rule Book. That same book also says that an Acclamator class ship can carry 2,000 tons of material. This implies that the assumed density for these conversions is 100 tons per cubic meter, or 100,000 kg/m^3. This gives the Trade Federation ship 500 million cubic meters of space. As a B-1 battle droid is only ~.3 m^3 while folded up, this translates to a carrying capacity of 1.6 billion droids. However, this neglects the space consumed by droid racks. Perhaps a better estimate comes from other ships – the Providence class has cargo capacity of 50,000 tons and can carry 1.5 million droids. As it is another ship built by the Trade Federation, it has the most potential accuracy. This density would result in a Lucrehulk carrying 150 million droids. This is again based off the stated cargo capacity, and this volume of space seems very low in light of the size of the craft; perhaps the rest of the volume is for B-2 batle droids, vehicles, landers, starfighters, and the rest. This would also correspond to a maximum capacity of 19.8 million for the coreship alone.
[4]
As quoted in the Galactic Republic Territory section, the galaxy has "billions" of worlds available to trade with. We will assume that the average planet has 10 “markets” on it, as it is said a market is a large commercial center, typically a single continent on a world. Now historically, western civilization has seen a mean annual growth of 3% for the past 150 years, corresponding with the start of the Industrial Age. Notably, this is a value roughly matched by the growth of China since they emerged from isolation in the 1970’s and began attempting to become a major industrial power. Thus we can use this value as a benchmark for a galactic scale economy. The markets alone would generate 10 octillion credits, and even if the companies saw only 0.01% of this in profits (an absurdly low market share for such a profitable venture) they would receive 1 sextillion credits annually. The Star Wars Databank – Trade Federation says that the Trade Federation has existed for 350 years, and at that profit margin with 3% annual market growth they would have a war chest of 36 octillion credits alone. The Confederacy was joined not only by them but seven other insanely profitable companies and one of the most wealthy men in the galaxy, and the Republic has been taxing at a greater rate for far longer.