Hi Jean Franco
I would have to double check the Modeling Gateway documentation to see if there is a way to export "some" containers or "some" global collections. If anyone else has some suggestion, please feel free to mention here.
As for upgrade to 10.2 with Huge Landscape handle, it would be considered a new install as the architecture is different enough where an upgrade from a previous version is not possible. However, you can either remodel your environment in the new install of 10.2, or you can use Modeling Gateway here as well, and export from your existing landscape and import into a new 10.2 Huge Landscape handle environment. The nice thing here is you could export using default options in modelinggatewayresource.xml as you want to export/import everything.
Here is a doc which mentions some upgrade scenarios and the benefits/considerations for each scenario:
Scenarios for upgrading to CA Spectrum 10.2