First- crafting isn't necessary to complete the game. You can find or buy almost any weapon or armor, as well as vehicle upgrades and mods.
Crafting is required to make the most powerful weapons and and armor, but even then it's the sort of thing you're probably going to do sparingly- you don't have to keep constantly crafting to stay ahead of the lethality curve
Augmentations used in crafting an item are recovered when you deconstruct it. Be sure to always deconstruct your custom-made gear, rather than selling it. Also be sure to remove any mods before selling items.
You do not need to buy, loot, or search for blueprints. They will automatically pop up in your inventory when available. You do, however, need to invest Research data into them to craft them.
There is not enough research data in the game to max out more than a few weapons or armor sets from each tech tree. Experiment with either found loot or low-level loot before pouring all your data into an item. Note also that there are many weapons you do not need to research in order to craft them- these include solid standbys like the Carnifex, Avenger, and (not quite as useful as before)Disciple.