Noob questions! Costumes with chasing lights

Hi! It's Noob-With-Stupid-Questions time! =)

I'm working on a group costume project that involves chasing lights in a 3-on 1-off marquis, and I just recently learned about e-textiles, soft circuitry, and the Arduino LilyPad -- pretty awesome, exciting stuff! Except that I have only basic electronics experience, and the more I try to think about this, the more my head just wants to explode =( I could use advice on... just about everything.

To start with, for a simple one-color marquis, I figured the LilyPad Simple Board would work? http://www.sparkfun.com/products/10274
Better yet, I suppose the old one would work just as well? LilyPad Arduino Simple Board (Old-School) - DEV-09725 - SparkFun Electronics

Then, to connect it to my computer so that I can program it, I use this cable? FTDI Cable 5V - DEV-09718 - SparkFun Electronics Or do I need a breakout board? This part is the most confusing to me, I am unclear whether one REPLACES the other or if they are used together.

Then obviously there's the lights themselves. Since the circuit is simple, I was thinking of just sewing a circuit with conductive thread ( http://www.sparkfun.com/products/10118 or http://www.sparkfun.com/products/10120 ? ) and individually sewing on LEDs. The problem is, the lights will be reaching all the way to our hands and feet -- I'm estimating 200 LEDs for my own costume. (?!?!) I have someone who can help me with working transistors into my design, but I dread the size of the battery pack that may be required. I might mention that we will be DANCING in these costumes (only 3 min)! There are also places where it would be nice to be able to "plug" a piece of the costume into the rest of the circuit -- for example, I have a belt that goes on top of my outfit. I thought about using snaps, but that seems rather clumsy... is there a better way?
Are there further complications I have not yet realized?... or an easier way to do this?? (some kind of string lights that don't cost an arm and a leg...?)

People keep asking me, "Why don't you use chasing Christmas lights?" Is there a way to even do that?? I have never bought any let alone tried taking them apart, so I have no idea how they're wired or if that would work somehow... anyone know offhand? =x

Thank you for your attention! .... I really don't know what I'm doing :~

One thing to consider is using addressable LED strings. This is exactly what I'm working on for a project for a show next year. We're using 50 RGB LED strings which are daisy chained together to make a longer string. We're still working out the power needed, but since the lights are never on all at once, we won't need some bulky and/or heavy pack. For a single string of 50, we can run them on 6V for hours. So even if we use 4 strings, and strap four 4-AA packs onto a belt, it won't be heavy for the wearer, but we're working on finding a different solution. The strings we use only require 2 pins (MOSI and CLK) so as long as whatever controller you're thinking of using has SPI, you're golden.

As for having "pluggable" pieces (such as the addition of a belt), that just requires some thought on how you want things to work. You could possibly make it so it's at the end of the string, or you can have a controller with multiple SPI outputs and use a second port for the belt ... different options here. You can also ignore SPI all together and go with bit banging and you can use any pins at that point.

The main difference between the Lilypad Arduino and the Lilypad Simple Board is that the Simple Board does not have Rx/Tx pins (receive/transmit), which are typically used in wireless communication -- for example if you were integrating a Lilypad Xbee board to your design. I believe it has less IO pins as well, if I am remembering correctly. So yes, using a Simple Board for your project should be fine.

The FTDI cable is essentially the same as the breakout board, and yes you can use this to program the board from your computer.

Given the number of LEDs you plan to use and the required power source, you will need to be using a transistor(s) on your banks of LEDs. A TIP120 will probably do the trick. Consider wiring them in Series/Parallel arrays, as used in LED matrices. Consider also that conductive thread is quite resistive. I always like to incorporate iron-on conductive fabric wherever possible, since resistance does not diminish over distance as with thread. I cut strips of conductive fabric and then join them to components using a few looping stitches of conductive thread.