All quoted source material is a copy and paste from purchased electronic copies of the rule books.
Narc and Artemis IV can't be fired indirectly.
"ARTEMIS IV FCS TW p. 130
LRM Indirect Fire: The Artemis system has no effect on LRM missiles fired indirectly."
"ARTEMIS V FCS TO pp. 283
Game Rules: Missile launchers using a functional Artemis V system apply a –1 to-hit modifier to the attack roll, and add +3 to the Cluster Hits Table (to a maximum modified result of 12). Aerospace units using Artemis V-enhanced launchers receive the same to-hit modifier only if all the launchers in a firing bay employ Artemis V, but determine the standard Attack Value as equal to a roll result of 10 on the appropriate-sized launcher on the Cluster Hits Table, delivered per the standard rules (as a standard-scale hit, in strictly aerospace combat, as with other missile systems, or as Clusters appropriate to the launcher type and size, when fired against ground units). Appropriate Point Defense rules may affect this damage value as normal. In all other respects, treat as Artemis IV (page 130, TW and pages 206-207, TM).
LRM Indirect Fire TW p. 130: The Artemis system has no effect on LRM missiles fired indirectly."
"NARC MISSILE BEACON TW pp. 138-139
Indirect LRM Fire TW p. 139 : Once a Narc pod is attached to a target, all Narc-equipped missiles may be fired indirectly at that target without a spotter; all other standard modifiers for Indirect LRM fire apply (see p. 111). In addition, if used in this manner, the Narc-equipped missiles lose their +2 modifier to the roll result on the Cluster Hits Table."
Based on the information provided you appear to be correct that Artemis IV FCS and Artemis V FCSor munitions equipped to use the FCS cannot be fired indirectly. Also based on the information above the Narc munition used to attach the beacon cannot be fired indirectly.
However, targets with attached Narc beacons can be hit by Narc equipped munitions can be hit by Indirect LRM fire.
ECM blocks both Narc and Artemis IV
"Narc ECM TW p. 139: Narc-guided missiles function like conventional missiles if the narc pod they are homing in on is within the “bubble” of an active enemy ECM suite; they do not receive the +2 modifier when rolling on the Cluster Hits Table (See ECM Suite, p. 134)."
"ECM TW p. 134:
Artemis IV FCS: ECM blocks the effects of Artemis IV fire control systems. Artemis-equipped launchers may be fired as normal missiles through the ECM, but they lose the Cluster Hits Table bonus."
"Narc Missile Beacon: Missiles equipped to home in on an attached Narc pod lose the Cluster Hits Table bonus for that system if the pods themselves lie within an ECM “bubble.” The Narc launcher itself (standard and iNarc) is not affected by ECM."