1 & 2: I have daisy chained 20 TPIC6B595 shift registers spread over 2 boards.
The up-to-40mA capable IO pins had no problems driving them at default SPI speed of 4 MHz.
I don't know how your new program does a ground plane, ground pour, or what it might call it. In eagle, you draw a polygon covering the area you want and then Name it GND. I do on the top & bottom layer because iteadstudio does 2 sided boards as standard. 1-sided is usually just home board creaters - I won't be bothered doing that when compex designs can be had & silkscreened & solder masked & have plated thru vias, all for $25 for 10 boards. (10cm x 10cm)
