Ahoj!
1) Ano, můžeš. Stačí, aby alespoň jedna polovina split karty splňovala podmínku, že je Instant a podmínku, že má CMC maximálně 2.
708.6. Some effects perform comparisons involving one or more split cards in a zone other than the stack or involving one or more fused split spells.
708.6a Anything that performs a positive comparison (such as asking if a card is red) or a relative comparison (such as asking if a card’s converted mana cost is 3 or less) involving one or more split cards in any zone other than the stack or involving one or more fused split spells gets only one answer. This answer is “yes” if either side of each split card in the comparison would return a “yes” answer if compared individually.
708.6c If anything performs a comparison involving multiple characteristics or values of one or more split cards in any zone other than the stack or involving multiple characteristics or values of one or more fused split spells, each characteristic or value is compared separately. If each of the individual comparisons would return a “yes” answer, the whole comparison returns a “yes” answer. The individual comparisons may involve different halves of the same split card.
2) Ano, přesně tak.
3) Fuse použít nesmíš, protože fuse je povoleno využít pouze, když split kartu hraješ z ruky (tady ale sesíláš z exilu).
702.101a Fuse is a static ability found on some split cards (see rule 708, “Split Cards”) that applies while the card with fuse is in a player’s hand. If a player casts a split card with fuse from his or her hand, the player may choose to cast both halves of that split card. This choice is made before putting the split card with fuse onto the stack. The resulting spell is a fused split spell.
4) Ano, pěkné interakce. To už je vyšší dívčí :-)