1.4 HDMI required for 3d? Need 1.4 splitter for multiple 3d devices?

1. There is no such thing as a HDMI 1.4 cable there is only:
Standard Speed cable
Standard Speed cables that support eithernet
High Speed cables
High Speed cables that support eithernet
Automotive HDMI cable.

For longer distance and if using a source/sources capable of 1920 x 1080p 60Hz or higher it is best to use High Speed cables.

The next part of your question is somewhat reversed.

2. You do not want a "splitter" you want a "switch".

Slimpified:
A "splitter" will take one source device, such as your Blu-ray player, and send that signal to mulitple display (sync) devices, such as a TV and a projector or mulitple TVs.

A "switch" will connect multiple source devices such as your, computer, PS3, X-box, satellite reciever or cable box, to one display device. You then select which device to watch on the switch (some are automatic).

3. Yes your switch needs to indicate in the specs that it supports 3D pass-thru. Do not look for just 1.4 because 1.4 does not require 3D support, 3D support is optional. As a matter of fact do not worry about 1.3 or 1.4 in your switch look specifically at the specs for the switch and look for support of 3D pass-thru.