Q1: Can I place just 2 Bagra Army trait Digimon cards from my trash as this Digimon's top digivolution cards for the conditions of this card's On Play When Digivolving effect?

No, you can't. A "by" condition can't be met if only some of the required actions are performed. The conditions for this On Play When Digivolving effect require you to place the specified number of cards from your trash as this Digimon's top digivolution cards.

Q2: If I use this card's On Play When Digivolving effect to place a card under a Tamer that already has cards under it, in what order do I place the cards?

If there are already any cards stacked under the Tamer, you place the new card at the bottom.

Q3: Can I use this card's On Play When Digivolving effect to place 1 card from my opponent's hand in the digivolution cards of one of their Digimon that isn't affected by effects?

No, you can't. If your opponent only has 1 Digimon that is unaffected by effects and no Tamers in their battle area, you can choose a card in their hand, but it can't be placed under that Digimon.

Q4: If I use this card's On Play When Digivolving effect to place a card from my opponent's hand under one of their Tamers, does that Tamer gain the placed card's inherited effect?

No, it doesn't. A Digimon will gain an inherited effect, but a Tamer doesn't gain it.

Q5: If I use this card's On Play When Digivolving effect to place BT12-038 GeoGreymon from my opponent's hand as the bottom digivolution card of their BT17-087 Marcus Damon that's treated as a Digimon, does that BT17-087 Marcus Damon gain BT12-038 GeoGreymon's inherited effect?

Yes, it gains the inherited effect. If BT17-087 Marcus Damon suspends, BT12-038 GeoGreymon's inherited effect will trigger. However, as soon as it is no longer treated as a Digimon, it will lose inherited effects.

Q6: When this card would be played, I placed EX10-056 Bagramon under it for its DigiXros, then I played this card. I then used this card's On Play When Digivolving effect to place 1 card from my opponent's hand as their Digimon's bottom digivolution card. This card's All Turns effect gives it EX10-056 Bagramon's All Turns effect at such times, but does it trigger from this card's On Play When Digivolving effect placing a card from my opponent's hand as their Digimon's bottom digivolution card?

Yes, it triggers.

Q7: I used this card's On Play When Digivolving effect to place 1 card from my opponent's hand as their Digimon's bottom digivolution card, then I placed 3 cards including EX10-056 Bagramon from my trash as this Digimon's top digivolution cards. This card's All Turns effect gives it EX10-056 Bagramon's All Turns effect at such times, but does it trigger from this card's On Play When Digivolving effect placing a card from my opponent's hand as their Digimon's bottom digivolution card?

No, it doesn't trigger.

Q8: I used this card's On Play When Digivolving effect to place 3 cards including EX10-058 Lilithmon from my trash as this Digimon's top digivolution cards and delete my opponent's Digimon. This card's All Turns effect gives it EX10-058 Lilithmon's All Turns effect at such times, but does it trigger from this card's On Play When Digivolving effect deleting my opponent's Digimon?

Yes, it triggers.

Q9: I used this card's On Play When Digivolving effect to place 3 cards including EX10-055 Tactimon from my trash as this Digimon's top digivolution cards and chose my opponent's EX7-061 Lilithmon (X Antibody) as the target to delete. This caused the 1st All Turns effect on my opponent's EX7-061 Lilithmon (X Antibody) to interrupt, and this card was chosen as the target to delete. This card's All Turns effect gives it EX10-055 Tactimon's All Turns effect at such times, but does it trigger?

Yes, it triggers. If the gained All Turns effect from EX10-055 Tactimon activates, this card will be prevented from leaving, EX7-061 Lilithmon (X Antibody)'s "by deleting 1 other Digimon" condition will no longer be met, and EX7-061 Lilithmon (X Antibody) will be deleted.