I've never owned an iPhone, but I think you both made good decisions. With Android devices, there is a lot of variance in terms of what you can do beyond manufacturer-specs. Some Android phones are "Google Experience" or "developer" phones, and these tend to allow for flashing of custom ROMs. The original Droid allowed this, and lead to the explosion of Android.
The Droid2 Global does not directly allow for flashing of new ROMs (yes, these are custom firmwares, and do often require wiping of all phone data for proper functionality). It can be rooted, which allows superuser access while inside of Android, but Motorola has locked the bootloader, which prevents any replacement ROM from being easily flashed from the Recovery console.
There is a lot of risk of bricking your phone if you flash the only available custom ROM (Fission), but as the other post mentioned, the SBF will be available soon. The SBF is a file that you flash onto your phone with Moto's RSDLite program using Windows. It restores a factory image.
Until that SBF comes out and you are comfortable using it, tread lightly. The stock experience on this phone is actually quite good, and the Android Market provides many "launcher" replacements that can replace your home screen operating environment. This is, to me, the biggest advantage over iPhone. We can use custom Home launchers (like Launcher Pro) instead of being restricted to one form of interaction and control. You will find everything you need to customize your phone within the Market, and most/many do not require root access or a new ROM.
Yes, avoid task killers. VZW sales people say they are "required," but that only shows how little they know about Android! Moto has actually included a rudimentary task manager application on the D2G anyway, so there is no need for another. The reason these are not needed is because Android is designed to automatically kill any unnecessary apps if another program has need for memory or processor use.