Well, pre-releases are incredibly casual, but I also get the impression that some of the technical rules aren't really followed or enforced, though that may be different wherever you plan to attend. But, I think that it would be even less strict if you just go to a store rather than one of the big ones. I'll tell you what I've experienced, but I'm not entirely sure that these are the actual rules.
Deck construction is timed. It's usually 35-40 minutes. You can get up when you're done. At the big pre-re's, you're assigned seating and build your deck there. At a smaller store one, I doubt this is the case, so you should be able to grab a table with Jeremiah and your brother and just deck doctor each other. Even if you can't get with your bro before the tournament starts, I'm pretty sure that there's actually a rules at pre-re's that says you can change your deck in between rounds, not just during sideboarding. So like, if you after round one you get a chance to look at your brother's stuff and see that he went Naya when his Esper stuff his better, you can completely remake his deck for him. Or it could even be as small as switching out a forest for a plains or whatever.
At traditional pre-re's, they wait until they have 24 (I think) people, and start a 4 round flight. If you go 4-0, you get 8 packs. 3-0-1 gets 6, and 3-1 gets 4. You keep what you open, and at the start of round one, you get a bonus pack just for playing, but it cannot be used towards your card pool. As far as how they can afford it, you've got to think that it costs $25-$30 to enter, and while retail value of the product is about $25, actual cost is probably closer to $18-$20. So about $7 extra for each player times 24, and you've got your prize pool. I'm not sure, but Wizards may even "subsidize" pre-re's.
As far as strategy goes, while standard blocks such as Time Spiral or Kamigawa are all somewhat similar, blocks that have a "build around me theme" (multicolor, tribal) each have there own distinct strategies. In this set, I'm thinking you're going to want to stick to a specific shard. So what I would do is start by organizing my pool into 11 piles: one for each color, one for each color triad, and one for (non-Esper) artifacts. The only tricky part there is that there is going to be two-color cards. Stuff like Ajani Vengeant is easy; he's still only playable in Naya. But then you have something like Branching Bolt (1RG) which is in both Naya and Jund. So you may want to even make five more piles: RG, GW, WU, UB, and BR, but I have a feeling each of those piles will only have like 1-3 cards each, so I'm probably not going to bother with that, and just pay attention instead. From there you should be able to prune off a couple of colors/shards, and be able to identify one or two of your strongest piles. Hopefully your stronger shard contains your strongest monocolor too. The three biggest things to look for are bombs, removal, and evasion. Usually Sealed Decks come down to who has the better bomb and who's comes down first, so if it comes down to two somewhat even options, if one's more consistent/has a better curve, but the other one's bombs are bombier, I'd tend to go with the bombs.
Here's the official page:
http://www.wizards.com/Magic/TCG/Events.aspx?x=mtgcom/events/prerelease-facts