yes, All gems in a linked chain effect every other gem.
You can have 2 active skills, with multiple supports. the supports then buffing each Active skill.
In MOST cases ORDER dos not matter. There are a few isolated instances where it does however. Order does technically follow, top right, in chain to bottom left.
The only time this matters, is when using some "trigger" abilities. Example, Curse on hit. Curse on hit, will apply the socketed CURSE, or Curses on hit, when using a linked active skillgem, that hits. Orb of storms for example. Now, normally, enemies can only have 1 curse applied to them from all sources. if you run, OoS+CoH+ 2 curses. lets say, Warlords mark, AND temp chains, in that order linked. The orb of storms will hit, applying Warlords mark, then ALSO instantly apply temp chains. Becuase the enemy can only have 1 curse, and its warlords, then tempchains. Warlords will be instantly overwritten. Swap the support position, and the opposite will occur.
And to be clear, its not alternating or anything. it is applying both curses on a single hit. however, they are activated in order of the links.
And of course there are ways to increase the curse limit. Occulist or items.
Also while at it, When a skill is given via an item, ALL sockets in the item effect the skill regardless if they are linked. example, " Grants
Level 1 Icestorm
Skill " Whispering ice does not need to be 6linked, only 6socket, for ideal.