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can someone more knowledgeable on this matter explain to me all the details regarding rarities of cards?

i'm talking about the older expansion sets... arabian nights, antiquities, legends, and dark. i know what the numbers mean like u3 means printed on the uncommon sheet and 3 times on a sheet. similarly, C5 would mean printed on a common sheet and appears 5 times on a sheet. my questions are:

1.) what is the ratio of rare sheets to uncommon sheets to common sheets? in other words for every rare sheet printed, how many uncommon sheets and common sheets were printed? (and for sets with only C and U, what is the ratio of common sheets to uncommon sheets?)

2.) how many cards were printed on a sheet?

3.) on magiccards.info, why is nameless race a rare and has the code C3? is that a mistake?

4.) in a booster pack, how many rares/uncommons/commons? is it always same amount or did it vary?

5.) in manalink, are cards just classified as rare, uncommon, and common or can we specify different levels as in the paper cards? e.g. U2, C3, etc.

6.) related to previous question, in sealed deck, anyone know formula used to generate booster pack? does every card have equal chance (if they are the same rarity) to be in a pack? i ask because it'd be cool if we could modify so that the booster packs are as close to real-life as possible!

thanks!

1) Not sure exactly, but you do have the right understanding of U3, C5, etc
2) No clue
3) No clue
4) From The Dark onwards, all boosters were 15 cards, with 1 rare 3 uncommons 11 commons. In some sets, basic lands were included as some of the commons; I don't remember if they were guaranteed or not, but they stopped doing that at one point. I know 3rd edition had basic lands in boosters, but memory fails about 4th edition. (I didn't buy base sets after that)

For some of the other earlier sets (Arabian Nights and Fallen Empires in particular) they didn't have rare cards. I know in particular fallen empires did not have enforced rarities in its boosters, because I remember one time buying five boosters and getting *zero* of the highest rarity card. I didn't buy boosters earlier than FE/3rd, so I'm not totally certain how it worked before that.

Oh, and FE boosters were 8 cards, not 15.

5) I think just as C/U/R. Shandalar does have one rarity called 'unique' for the uber cards, like Ancestral Recall.
6) My understanding is that except for the C5/U3/etc, all cards of one rarity are equal in chance to cards of another rarity in that booster, at least in real life. In manalink, it sure seems like certain ones show up a lot more than others, which is one reason I don't like playing sealed deck.

Arabian, antiquities and the dark boosters were 8 cards as well, therefore they had only uncomons instead of rares. U1 for quite uncommon and U3 for pretty common.
Homeland was the last set with 8 cards boosters.
Alliance was the last set which didn't have 15 cards set. alliance had 12 cards boosters. with 1 rare and 2 uncos. some with a U1 rarity, some other with a U3 rarity. 2 rares from that set had a R5 rarity (and not the best one unfortunatly, but it's ok since Alliances really was one of the best sets ever.)
starting from 4th edition base set boosters didn't contain basic lands anymore. as one who bought quite a lot of 3rd edition boosters, I can tell you this was a relief : I was sick and tired of booster full of basic lands; because at the time there were more than one. sometimes 3 or 4.