I'm a newbie, and I've got a few questions

I'm planning on building a pair of TW (tweeter over woofer right?) 2 way speakers and a separate sub enclosure. I've been doing research for a while and after initially being quite overwhelmed, I decided a good place to start was choosing the drivers. These are what I've chosen so far based on performance and price (I'm a student on a limited budget):

Sub = Adire Shiva $115 or so
Tweeter = Seas 25TFFC $25/each
Vifa D27TG-35 $25?
Midrange/Woofer = Monacor SPH165KEP $35/each
Peerless 850108 $30?
Vifa P133WH $30?

They are in the order of preference. I've looked at FR graphs on them all. I'm curious if anyone has reccomendations on what I've chosen, in the area of ease of crossover design, enclosure design, etc. I also need to know about sub amp reccomendations.

As this will be my second DIY speaker project (first was a 2.? cubic ft sealed enclosure for an Aura Force 12 that would fit flush with the angled back seat of my car. Qtc of about .707 before any cabin gain) I want to keep it all sealed if possible (simplicity) and the crossovers passive (simplicity and cost, passives are the right choice correct?).

I'm budgeting $400 for it all, because I will need to get a new reciever/amp to replace my current Technics one (it only has two lines out and no sub out).

Sorry this was long, but I hope to build these within the next year and want to get as much info as possible so I don't make TOO many mistakes.
Well the Theile/Small parameters are unique for each model of driver. Any decent driver manufacturer will provide these measurments for you. But you can measure the parameters on your own once you get the drivers. The book does tell you how to do that. Really this would probably be MORE accurate, but that is a personal decision, to do it yourself or use the figures they give you. Their numbers are usually an average of that particular model number and of course there will be slight differences in every indivudual driver of the same design. But I never considered it worth the time and expensse to do it myself, I always used the published data.
And yes there is detailed informationn for crossover design with formulas in the book.
And I think that it is worth pointing out that most manufacturers will provide suggested alignments, with box volume and everything. I am thinking of most of the major companies, Vifa, Dynaudio, Peerless, Scan-speak, Focal etc.
Building a good loudspeaker is more of a challenge than it might appear. If you were to ask me, I'd advice you to first focus on the 2-way monitors, and then after you're pleased with the results build a sub to match them where you feel they are lacking. A 2-way monitor is the place to start for a newbee, you got that right, though that doesn't mean it's an easy undertaking to design one from scratch (choosing your own drivers, designing crossover, etc). You can design boxes by WinISD and build crossovers by the formulaes, but to get it right you will need to listen to it alot, reference with other systems to keep an objective POV, get others to listen, tweak values, tweak bass port, components (carbon vs film vs wirewound resistors, different types of capacitors, coils, blah) When you finally get the sound you want, you start building the sub if you feel you need one...

Sealed 2-way monitor is not very feasible though it's definitly easier to get right than BR. You do need a very big box and you will get incredible poor bass response. Focus on your monitors, build them bass reflex, leave the sub for now, keep your technics, and put the extra bucks in the monitor drivers. I'm not the one to advice you about budget drivers, but I think some guy named geenius' pages on his "Hatt" monitors might be interresting reading for decent budget 2-way.

Just my :2c:

Good luck.