Quick question as the RAW don't seem to be clear but does seem to suggest ex. 1 as correct. (unless I just missed it).

when you hit with a linked weapon do you resolve each individual hit against the opponents soak or do you total the damage of all hits then resolve it against soak.

ex. 1: I roll 1 success, 2 ad. weapon dam is 5 against 5 soak for no wounds; spending 2 ad on linked would be pointless because again 0 wounds.

ex 2: roll 1 success, 2 ad. weapon dam is 5 against 5 soak, spend two advantage on linked for 2 hits, 10 damage against, 5 soak for 5 wounds.

Each hit separately.

ex. 1 is correct, but there are many options even if the attack didnt do the damage, add boost dice, recover strain, extra maneuver

So in your example you don't mention adding the success to the weapons damage. I assume it's just included in the weapons damage (4+1), but I thought it better to check.

In your example 1, if the attacker had scored 2 success then they would have managed 2 damage on their target ie. 4+2-5=1, with linked making that 2x[4+2-5]

This also means that each hit of a Linked weapon can inflict its own separate critical hit (instead of just one and +10 per additional) if you roll enough Advantages and/or Triumphs.