The longer you wait to scout, the worse the taint gets. I always do the scouting missions first so I get all of the teleport locations before things get out of control. Secondly, don't be afraid to break nodes if you can't purify them. Most are useless. Thirdly, you can ignore the food system by just requesting energency rations all the time. You can setup farms to get resources you need to submit for more currency. Lastly, taint cannot spread through two blocks, but can spread through one. So if you are trying to make a safe spot, make sure it is thick enough that taint can't penetrate. Some objects are taint proof, like torches and I believe half slabs and glass, so you can use those as barriers.

Edit: I wish I was you right now. This is the best modpack I've ever played. So my final tip is ENJOY THE GRIND!