Hi remco. Well I'm not an expert at all the info you need but I'll try.
Muzza died on the glider when it was hit by a flak. So that's one less in Baker's squad already. I don't think Baker and Mac are included because Mac is a Staff Sergeant so Baker wouldn't be ordering him about. I think Baker just included the men under his command.
I think that the men are hardly ever all together because Baker leads the assault team and Red leads the fire team. There kinda both leading there own team doing different things. They do meet up in some missions where Baker can command both the fire and assault team. I'm sure that there are plenty of other people who can help you more than that. Hope this kind of helps. I'll try and help you again if you need anymore help.
The Baker's Dozen comes from Colonial America where bakers were hung for making the loaf light. That is why they give 13 instead of 12. Additionally, they decided to use the Avoirdupois pound instead of the Apothecary. The Avoirdupois weight is the French standard of dry measure. All of our dry measures in America today (tsp, tbsp, cup, etc.) are Apothecary except the pound which is still Avoirdupois. The Avoirdupois pound is 30 grams heavier than the Apothecary measure.