/diy/ - Do It Yourself

I'm working with a CD4040 right now, and I was having a problem with flickering led outputs (esp. when the board was tapped/moved). To solve this, I added pull-down resistors to every input and output, just to be safe. From looking online though, it seems like pulling down outputs is completely unnecessary -- is this true? When I tried removing some of the unused outputs' pd-r's, the flickering problem started again. Are tied down outputs necessary, or is this something entirely to do with breadboards/parasitic capacitance?

Electronics newbie here, I've been messing around with shift registers and a CD4040BE (full analog), and while I've gotten both to work, the behavior is unstable.
While reading through the CD4040's datasheet, I saw it outputs at around 1-7mA, but the maximum input is listed as "+/- 0.1microamps." What the hell does that mean? Should I be putting a 50Mohm resistor in front of my input, or does it just need an extremely stable current? Is there a general rule for what current can be used for these sorts of counters/logic series, or is it all case by case? The abstract/first paragraph says the max input is 1microAmp at 18V, so should I just use 1microamp for 5V?