Rick, no such thing as "too bold" on this forum. I built my car from advice from this forum and am still learning. You'll find the comments you get are uncensored and most often VERY accurate. I have learned in my short experience in road racing that it is not as much about the car as it is the driver, so some of the national level run-off contenders with FASt cars on this site will give you GREAT advice for your car. You'll see.
As far as your questions:
Any, 1 5/8 " long tube header will work just fine. There has been some recent discussion about stepped headers and the jury is still out as to their legality. IF you are using the GT40P heads, you may have some problems with the plugs & wires since the plug angle on those heads causes interference/contact with the primaries, specifically on #4. The new AS Edelbrock heads are out, make more power, and do NOT have the plug interference problems.
You really do not need a 9". they are heavier and more expensive. A 8.8 will work just fine with 28 spline Moser (or other aftermarket) axles. save the $$ and spend it on a torsen style, road-race differential.