Questions about the Calvin cycle and the Krebs cycle?

During the Calvin cycle, an enzyme referred to as rubisco (RuBP carboxylase) catalyzes the attachment of CO2 from the atmosphere to a five-carbon sugar, ribulose bisphosphate.  The resulting six-carbon fragment is split in half, forming two molecules of 3-phosphoglycerate (3-PGA).  This phase is referred to as carbon fixation.  During phase 2, which is the reduction phase, 3-PGA receives a phosphate group from ATP, and is phosphorylated to 1,3-bisphosphoglycerate.  Finally, electrons from NADPH are transferred to 1,3-bisphosphoglycerate, reducing it to a three-carbon sugar, glyceraldehyde-3-phosphate (which I'm assuming is the same as phosphoglyceraldehyde, or PGAL).

For your second question, the pyruvate generated from glycolysis is converted into acetyl coA before it enters the Krebs (citric acid) cycle.  During the formation of acetyl coA, pyruvate's carboxyl group (-COO) is removed and given off as a molecule of carbon dioxide.  Additional molecules of carbon dioxide are produced during the Krebs cycle as well, as glucose is further oxidized.  The first step of the Krebs cycle involves the attachment of acetyl coA to oxaloacetate.  This generates the first product of the Krebs cycle, citrate.

The oxidation of glucose releases electrons and hydrogen atoms that are transferred to NAD+ and FAD.  This generates NADH and FADH2.  The electrons and hydrogen ions stored in NADH and FADH2 are utilized during oxidative phosphorylation to create up to 38 molecules of ATP.

I hope this helps!  And I hope it is not too complicated.

I forgot to add that citrate is the ionized form of citric acid, just as oxaloacetate is the ionized form of oxaloacetic acid.