look at device manager and it should list the details for the bluetoth device.
and no you can not upgrade it. it is hardware based and not software that can just be updated. you can update the bluetooth device to a new one if its not the generation you want. they are rather cheap really whether for laptop or desktop.
not really. new version bring more bandwidth and sometimes new features. you'll have to look and see if its worth it to you. keyboards, mice and the like that use bluetooth don't need the bandwidth available now. so it's unlikely you need to upgrade. bluetooth does support data transfer but it's not a good choice in any way really. so many other ways to swap data rather than the slow bluetooth protocol