I would guess your first two questions would be:

Well, you spindle for the same reasons you don't just buy a completed sweater, hat or whatever at Wal-mart, or the Gap.
1. You can't quite find the weight of yarn you like.
2. You can't find the color you like.
3. You want to combine some vanilla yarn with some frou-frou and just holding them together as you knit isn't giving the effect you want.
4. You are a total control freak and want to micro-manage every aspect of your project from raw material to finished product.
5. You are looking for something even more meditative than knitting.

Next two questions:

Yes, a spindle is slower by the hour than a spinning wheel, but you can't just drop you spinning wheel in your tote and pull it out when you?re in line at the bank. Or take your wheel backpacking in the Montana mountains. Yes, there are portable wheels, but they do have their limits. A spindle too is much easier to keep safe from small children, large cats or other picky-fingered housemates than a wheel is.

So you've decided to spindle. Now what? There are a lot of different spindles out there. How do you choose? What do all of these word mean? Drop spindle? Hand spindle? Top whorl? Bottom whorl? What's a whorl? Takhli? Turkish spindle? Akha?

At the very basic there are three types of spindle: top whorl, bottom whorl and supported. The whorl is the disk or ball that provides the weight to keep the spin going. All three types are handspindles. Top and bottom whorl are both types of drop spindles. Drop spindles can spin almost any fiber you want from dog hair to flax to wool to Ingeo to silk.

A typical top whorl spindle looks like this: {insert top whorl spindle}
It has a hook on one end above the whorl and a shaft below the whorl for storing your finished yarn.
Top whorl spindles can come in many weights and sizes. {insert three top whorls} Top whorl spindles usually spin faster and quite often are lighter than their bottom whorl counterparts. They are great for very fine, lace weight yarns. They also usually are quicker to load since they have no need of wrapping or half-hitching to keep your yarn on the spindle.

A typical bottom whorl looks like this: {insert bottom whorl spindle}
A bottom whorl spindle usually just has a shaft and a whorl. Finished yarn is stored above the whorl. To keep the yarn on the spindle you usually have to do some wrapping and half-hitching.
Bottom whorl spindles also come in various sizes and can have hooks or notches at the top of the shaft. {insert three bottom whorls}Bottom whorl spindles are usually less bouncy, spin longer and are better for plying yarns on than top whorl spindles.

Of course, you can find rabid advocates of either top whorl or bottom whorl spindles. Just like you can rabid advocates of various types of needles or yarns or knitting accessories. Your best bet is to take a few spindles for a test drive and decide what you like.

Supported spindles are a lot less common in both availability and usage. Again they can have hooks or not. They can have bead whorls or flat whorls. One end of a supported spindle sits in a bowl or some other shallow container and the working end hangs free. The spindle is spun twist builds up in the yarn. The spindle is stopped and the twist is drafted out into the yarn. These type of spindles are best for spinning very short fibers like cotton or dryer lint. A Takhli is a type of supported spindle.
So, you?ve decided what type of spindle you want and you?re looking at spindle ads. They talk about featherweight, or .05 oz, or maxi, or boat anchor. What are they talking about? It?s all about weight. The weight of your spindle to a great extent dictates how thick, or heavy your yarn can be. You can'tspin lace weight yarn on a really heavy spindle and you can'tspin bulky yarn on a featherweight. Starting out, unless you?re really sure you are planning on always making lace or super bulky hats or only plying commercial yarns, you should choose a spindle that weights somewhere between 1.5 to 2 oz. This is a nice medium weight.

Okay, you decided on the type. You?ve decided on the weight. Where to buy a spindle? If you have the opportunity, go to a wool or fiber festival where you get your fingers on a several spindles and try them out. Or find a local spinning guild and do the same thing. A spinning guild has the advantage of usually having a ?spindle person? who can give you pointers on how to use your spindle. Lacking one of those, hit the web. You can find spindle reviews, spindler mail lists and spindle vendors. You can even find directions for making very inexpensive spindles out of old CDs and dowel rods. My suggestion is if you go this route don'tlay out a ton of money. Buy something on the less expensive side and see if you like it.

You?ve bought your spindle and started fiber and they are staring you in the face. Where to learn how to spindle? A great book is Spindle Spinning from Novice to Expert by Connie Delaney. This small book will take you through the basics. On the web try www.icanspin.com or Interweave Press? site. Both have well written instructions. Or find one of those "spindle people" at a spinning guild. If you're in Chelsea, MI on the second Saturday of the month I'd be that spindle person.
Pick up a spindle. You?ll be surprised how fun and relaxing it really is. You might even start looking at your knitting as sucking away your spindle time.