there should be an option on the poser export to keep the model merged.

If you are still getting separated bits in Maya, run the merge vertices command with a low tolerance value of say around .01

Also when binding a model to a rig it will bind all that you have selected. You can of course choose to select and bind as you see fit and not all in one go. Things like eyes, hair tongues and so on can be parented to the rig instead of being skinned, which can make life easier.

Jay