Accepted Solutions
> 1. If I start a new clean installation (Windows XP first, then individual softwares/applications), can I export some kind of preference/settings from the original system and then somehow import them to the VM?
That all depends on the Operating System, the target applications and what migration tool you choose to use.
2. I heard that we can have multiple VMs (even with the same operation systems, such as XP) in the same Mac OS X/Fusion2 in the same physical MacBook. (For example, some VMs have many software/applications installed but some are clean with the minimal amount of software/applications.) In this kind of scenario, will those software/applications consider themselves as in the same hardware and thus don't require additional activation/registration, or do I need to repeat the whole process for each individual VM? How about if I want to copy the VM from a physical MacBook to another machine (for example, a Mac Pro)?
Licensing issues aside you can have as many Virtual Machines running of the same or different type as limited by your available resources like RAM and disk space.
As far as Licensing go you are required to have valid licenses, and or product keys, and or serial numbers and or product activations as required by the EULA of the products in question and if your thinking about building out a Virtual Machine and propagating it then you best be using Volume Licensing Media and hold requires number of licenses otherwise you will undoubtedly run into product activation issues in some cases and not only with some OSes but also some software packages as well.
Also you will have network connectivity issues if you try using an exact copy of an original Virtual Machine at the same time on the same subnet and the required changes necessary to avoid such conflicts can under certain circumstances trigger OS and or software product activation.
Does this answer your questions? 
> 1. If I start a new clean installation (Windows XP first, then individual softwares/applications), can I export some kind of preference/settings from the original system and then somehow import them to the VM?
That all depends on the Operating System, the target applications and what migration tool you choose to use.
2. I heard that we can have multiple VMs (even with the same operation systems, such as XP) in the same Mac OS X/Fusion2 in the same physical MacBook. (For example, some VMs have many software/applications installed but some are clean with the minimal amount of software/applications.) In this kind of scenario, will those software/applications consider themselves as in the same hardware and thus don't require additional activation/registration, or do I need to repeat the whole process for each individual VM? How about if I want to copy the VM from a physical MacBook to another machine (for example, a Mac Pro)?
Licensing issues aside you can have as many Virtual Machines running of the same or different type as limited by your available resources like RAM and disk space.
As far as Licensing go you are required to have valid licenses, and or product keys, and or serial numbers and or product activations as required by the EULA of the products in question and if your thinking about building out a Virtual Machine and propagating it then you best be using Volume Licensing Media and hold requires number of licenses otherwise you will undoubtedly run into product activation issues in some cases and not only with some OSes but also some software packages as well.
Also you will have network connectivity issues if you try using an exact copy of an original Virtual Machine at the same time on the same subnet and the required changes necessary to avoid such conflicts can under certain circumstances trigger OS and or software product activation.
Does this answer your questions?