I'm a beginner bowler and am in the market for my first bowling ball. 
But, bowlers evidently have their own secret language that newbies
couldn't possibly understand when describing various types of bowling
balls.

So my first questions are about terminology.  For instance, how the
heck do things like differential, flare, radius of gyration, break
points, length, weight blocks, and coverstock affect bowling balls? 
Also, when drilling a ball, bowling folks will say things like "this
one came with 3.7 top and a 3 inch pin. I set it up with the pin under
the bridge ( 5 inches to PAP ) and the cg kicked out about an inch." 
Huh?

My second question: what type of bowling ball should I choose based on
my bowling style and how should I have it drilled?  Could you possibly
recommend a specific brand and model?  I use a thumbless delivery with
an average ball speed of about 15mph (measured at a local bowling
alley with a 15 pound house ball).  Because of the thumbless delivery,
I generate a considerable hook, even with the plastic house balls. 
Thanks,

withers

Hello Withers,

Wow. I have bowled occasionally for years, but have never encountered
most of those terms. However, there are a few good sites that provide
this kind of information. As a first choice, I suggest:
  http://www.bowlingcoach.com/CEOct02.pdf
which is a 40 page PDF file, written for a bowling coach, defines a
number of terms (those you mention and many others) and describe the
factors that affect a choice of bowling ball. To summarize the terms
you mentioned and try to put them into perspective:

Radius of Gyration - a ratio of rotational inertia and mass. It
basically tells you if the weight is concentrated in the center of the
ball [smaller values] or closer to the surface [larger numbers]. A
smaller radius of gyration allows you to spin the ball faster (and get
more effects).
Differential - the difference in the "radius of gyration" along the 3
axes (DRG). Higher values of DRG will tend to cause the ball to curve
more. [other factors affect curve as well]
Flare - a measure of how the axis of rotation changes as the ball
travels down the lane. Flare is dependent upon the DRG and how much
rotation you apply to the ball.
Break Points - where on the lane the ball will "break" (move across
the lane). There are several factors that can affect this.
Length - This doesn't have a clear definition - it can vary by
manufacturer but is supposed to indicate the distance down the lane it
will arc.
Weight blocks - added to modify the inertia (and to a lesser extent -
weight) of the ball. Placement of weight blocks will affect the radius
of gyration and usually the DRG.
Coverstock - the material used in the surface of the ball.

From your quote...
Also, when drilling a ball, bowling folks will say things like "this
one came with 3.7 top and a 3 inch pin. I set it up with the pin under
the bridge ( 5 inches to PAP ) and the cg kicked out about an inch." 

There are several acronyms buried in this brief quote, in particular:
  the PIN is basically a balance point related to the weight block
[odd - PIN isn't defined]
  the PAP is basically the point on the ball opposite the lane when
releasing [a reference point]
  the CG is the center of gravity, marked on the ball surface by the
manufacturer by floating the ball on air
There are several charts in the reference that relate a number of
these terms and describe the effects on the balls.

The type of ball for each type of bowler is summarized in the last
three pages. Basically, it depends upon your speed of release (appears
to be a moderate value) and rotational speed (something you may still
want to measure). A lower speed and rotational value suggests a
shinier ball and an aggressive ball. A higher speed release and
rotational value suggests a duller surface and less aggressive ball.
Based on what you stated - you may need something in between but I
suggest you get the rotational speed measured to be sure.

A few other references that have some good material include:

A number of individual bowling ball (and related product) reviews and comments
  http://www.ballreviews.com/
  http://www.epinions.com/sprt-All-Bowling
A set of personal reviews of balls and includes several explanatory
links at the end; note he may have a much higher release speed and
rotational velocity, so take the specific comments with some caution.
  http://www.angelfire.com/il/A300bowlingballs/

Or search using phrases like
  "first bowling ball"
  explain motion bowling ball
  (insert a phrase here) "bowling ball"

Let me know if you need further explanations on the terms you referred
to or if some part of the answer is unclear. I would be glad to
respond to clarification requests with the additional information
needed.

  --Maniac

I recommend that you go to a professional bowling pro shop and let an
expert find the right ball for you. As a beginner, you'll have little
idea what balls might help or hinder your game. Yes, you'll pay a
little more for a ball bought from a pro shop (as opposed to, say, a
ball bought from any store with a big sporting goods section), but
you'll get a ball that's good for you: weight, material, balance, type
of holes drilled, inserts in the holes, etc. A pro might even take you
to the lanes and watch you throw a few balls before making a ball
recommendation.

G'luck,
dtc

This website is an excellent glossary of bowling terms:

http://www.bowling2u.com/trivia/glossary/glossary.asp

This forum discusses your question about what kind of bowling ball you should get:

http://www.bowlingindex.com/bowlingboard/read.php?TID=1144&page=1

Bowling is a wonderful sport, something you can enjoy your entire life.

I agree with dancethecon.  Your local pro shop proprietor is your
friend and can helpful in more ways you can imagine.  Of course, he
wants to sell you a ball, but will prove invaluable in guiding you on
the right choice.

Frankly, if you're a beginning bowler, all these things you're
mentioning really don't matter - so I wouldn't spend a lot of time
worrying about it.  If you throw it in the gutter, no amount of
differential, flare or breakpoints will get it out. =)

I would suggest focusing on the basics and learning to bowl correctly
from the start.  As your skills improve and you have consistent
control with the ball, then you might consider exploring the questions
you're asking about.

Hope this helps.