Timed nodes are really a joke. The scrips you get from Custom Deliveries will make up the bulk of your scrip exchange for tokens. However I'd say for an easier time do them as Crafters, since crafting them is much quicker then gathering since you just buy the mats at the Iddylshire for the 50-60 ones.

ARR/HW/SB hunts are a good way of getting them on top of the dailies. If you also like to PVP at prime time, running frontlines will get you them quickly too. But I'd say Hunts and Dailies are the two best ways of getting them, especially if you tank/heal for quick queues.

They are all usable but i don't believe you can purchase any until the weapon is completed. Someone else can correct me if I'm wrong, but the node will sell you the replicas after you make the last one. I believe they changed it in Eureka though.