First, what version are you running? I ask because with newer versions you have additional options.

Your first question: The answer is no. There is no maximum size. The -d 2gbsparse is basically an export option, but they won't tell you that. If you are running 3.5 or 3i there is an OVF appliance that you can run that can convert the vm into smaller files and is a bit more efficient that the 2gbsparse option.

Question 2: I am afraid that this is not even an option. With either option I described above you are required to convert the vm back to one of the standard formats. It will not run from the 2gbsparse or the OVF format.

HOWEVER: If it is size that you are worried about you can create your VMs to dynamically allocate space using the thin format option. There are some pretty good docs regarding disk format on the site.

Regards,

Paul