You Need That ResistorThat resistor on the data line? Yeah you need it. Otherwise you might blow an LED which renders the entire rest of the strip useless. If that happens cut out the first LED and solder the power and data lines directly to the second LED.
You Want Shorter, Thicker, WiresUsing jumper wires, of the 300-for-$5 variety is fine for a few LEDs. If however you have 300 LED drawing around 1A then those thin wires have non-negligible voltage drop. For me this was on the order of 0.7V or more. This means even though my power supply was putting out 5V the LED strip was only seeing 4.3V, causing flickering of the LEDs.
For any piece of wire the voltage drops increases with current simply because of V=IR. Thicker wires have less resistance per unit length and therefore less voltage drop per unit length.