As a side note, Judith's best friend is Electrickery. Who says Izzet and Rakdos can't get along?

Well, yes, but actually no, for two different reasons.

Deathtouch and lifelink are just keywords, and Judith, Carnage Connoisseur can apply them to any spell, as the ability says. However, those keywords only apply when something deals damage.

First reason: Disfigure gives a creature -2/-2, and that's it. It does not put -1/-1 counters on the target, and it does not deal damage. Neither deathtouch nor lifelink will apply here.

Second reason: Even as a 1/1, your friend's indestructible creature cannot be destroyed. Since deathtouch has the effect of "whenever this deals damage to a creature, destroy that creature," indestructible nullifies it.

To deal with an indestructible creature, you generally need to exile it, reduce its toughness to 0 or less (at which point it will die without being destroyed), or force the opponent to sacrifice it. Something like Disfigure is usually ideal for the job—it just wasn't big enough in this case. Grasp of Darkness would have worked perfectly.

Usually, Judith, Carnage Connoisseur wants damage spells like Lightning Bolt for removal, though those will have issues with indestructible. On Disfigure, you'd just use the Imp mode of her ability.

Xenograft's type-changing ability is a static effect, which means each of your creatures will enter the battlefield as a Scarecrow. They will trigger Reaper King. They will not be Scarecrow cards in you library, graveyard etc for effects that search for creature types, and they will not be Scarecrow spells on the stack, but they will be Scarecrow creatures at all times as long as you control them.