Q1: If my opponent's [[ST18-03|ST18-03 Falcomon]] attacks and this card switches from unsuspended to suspended, can I activate this card's Opponent's Turn effect?
Yes, you can.
Q2: Can I use this card's On Play When Digivolving effect to suspend either my Digimon or my opponent's Digimon?
Yes, either can be suspended.
Lv.5 Cherrymon BT21-050 U Ultimate | Virus | Vegetation/WG [Digivolve] Lv.4 w/[WG] trait: Cost 3 [On Play] [When Digivolving] You may suspend 1 Digimon. [Opponent's Turn] [Once Per Turn] When one of your opponent's Digimon attacks, if this Digimon is suspended, you may change the attack target to 1 of your Digimon with the [WG] trait. --- Inherited: [All Turns] [Once Per Turn] When any of your [WG] trait Digimon are played, you may suspend 1 of your opponent's Digimon.
Lv.5 Cherrymon BT21-050 U Ultimate | Virus | Vegetation/WG [Digivolve] Lv.4 w/[WG] trait: Cost 3 [On Play] [When Digivolving] You may suspend 1 Digimon. [Opponent's Turn] [Once Per Turn] When one of your opponent's Digimon attacks, if this Digimon is suspended, you may change the attack target to 1 of your Digimon with the [WG] trait. --- Inherited: [All Turns] [Once Per Turn] When any of your [WG] trait Digimon are played, you may suspend 1 of your opponent's Digimon.
Lv.5 Cherrymon BT21-050 U Ultimate | Virus | Vegetation/WG [Digivolve] Lv.4 w/[WG] trait: Cost 3 [On Play] [When Digivolving] You may suspend 1 Digimon. [Opponent's Turn] {{OncePerTurn}} When one of your opponent's Digimon attacks, if this Digimon is suspended, you may change the attack target to 1 of your Digimon with the [WG] trait. --- Inherited: [All Turns] {{OncePerTurn}} When any of your [WG] trait Digimon are played, you may Suspend 1 of your opponent's Digimon.