I need to select a platform for creating indicators. I've read some people are using Visual Studio, others are using Visual Studio Express, and others SharpDevelop. The latter two are free but lack debugging functionality compared to VS Pro.

1) Are there any other reasons to select one platform over the other?

2) If I use Visual Studio, I might be able to get my hands on an older version of VS Pro. Should I stay away from older versions of VS Pro?

3) I tried compiling the SMA example in "Creating an Indicator Library in Wealth-Lab Pro" with Visual Studio Pro 2008 but ran into some errors. The PC I was using did not have Wealth Lab Pro installed.
3a) Do I need to compile my code on the same platform where Wealth Lab Pro is installed?
3b) Is VS Pro 2008 too old?

Thanks again.

Your information is outdated. Starting from VS2012 (and there's VS2013 already), Express versions contain Attach to Process debugging and hence can be considered equally powerful for the typical task of debugging a library for Wealth-Lab. When starting out, one certainly does not need the feature set and complexity of Pro/Ultimate versions.

Forget VS2008, it's absolutely useless since version 6.4. The minimum version required to target .NET 4.0 was VS2010 but I recommend getting the latest VS2013 Express. For the whys and wherefores, check out this discussion: Start learning C# with Visual Studio programming environment