have a look into PDM i think it comes free with every version of SW
I work directly from our network, and never download or save the files locally. With that being said, Pack and Go is probably the way to go if you do need to work locally. Pack and Go from the network to your hard drive, and when you're done Pack and Go back to the network.
I do this periodically (with large assemblies):
1) Pack and go the entire assembly (and drawings) to a specific folder on my hard drive.
2) Back on the network, rename the folder that the project is in and append it with "WORKING OFFLINE" & today's date
3) Move that entire folder into an archive folder.
4) Work on the assembly locally as needed.
5) When done, Pack and Go back to the network to a new folder with the project name.