can anyone refer me to someplace where i can find more information about when/how to use the I 601? specifically, i am looking for guidance about how to use it in conjunction with an application for a K1 visa. is it necessary to complete the I 601 for someone who was an undocumented worker in the US and now wants to reenter the US with a K1?

Look at the pinned Guide when to use a 601, you can also go to 601 moral support, I'm sure someone there can help answer your questions. You might also check out immigrate2us.net under 601. I hope this helps, I'm sorry I can't be of any more help.