Abilities that Slivers grant, as well as power/toughness boosts, are cumulative. However, for some abilities, like indestructible and the ability granted by Belligerent Sliver, having more than one instance of the ability doesn’t provide any additional benefit.

The Sliver that enters the battlefield is the source of the ability that exiles the creature. For example, if a blue Sliver enters the battlefield under your control, the ability can target and exile a creature with protection from white.

If you change the creature type of a Sliver you control so it’s no longer a Sliver, it will no longer be affected by its own ability. Its ability will continue to affect other Sliver creatures you control.

Auras attached to the exiled creature will be put into their owners’ graveyards (unless they’re Theros block cards with the bestow ability). Equipment attached to the exiled creature will become unattached and remain on the battlefield. Any counters on the exiled creature will cease to exist.

When Constricting Sliver enters the battlefield, the ability it gives itself will trigger.

The exiled card will return even if the Sliver whose ability exiled it doesn’t have that ability at the time (perhaps because Constricting Sliver is no longer on the battlefield).

If a Sliver leaves the battlefield before its enters-the-battlefield ability resolves, the target creature won’t be exiled.

If a Sliver you control leaves the battlefield, only the card that particular Sliver exiled will return to the battlefield. Each card exiled by another Sliver will remain exiled until that Sliver leaves the battlefield.

In a multiplayer game, if the Sliver’s owner leaves the game, the exiled card will return to the battlefield. Because the one-shot effect that returns the card isn’t an ability that goes on the stack, it won’t cease to exist along with the leaving player’s spells and abilities on the stack.

The exiled card will return to the battlefield under its owner’s control.

Slivers in this set affect only Sliver creatures you control. They don’t grant bonuses to your opponents’ Slivers. This is the same way Slivers from the Magic 2014 core set worked, while Slivers in earlier sets granted bonuses to all Slivers.

Constricting Sliver gives Slivers you control an ability that causes a zone change with a duration, a newer style of ability that’s somewhat reminiscent of older cards like Oblivion Ring. However, unlike Oblivion Ring’s abilities, this ability creates two one-shot effects: one that exiles the creature when the ability resolves, and another that returns the exiled card to the battlefield immediately after the Sliver leaves the battlefield.

If a creature token is exiled, it ceases to exist. It won’t be returned to the battlefield.

The exiled card returns to the battlefield immediately after the Sliver leaves the battlefield. Nothing happens between the two events, including state-based actions. The two creatures aren’t on the battlefield at the same time. For example, if the returning creature is a Mercurial Pretender, it can’t enter the battlefield as a copy of the Sliver.