Short answer. Yes to both. Article 564 of the Civil Code lets a usufruct be constituted on the whole or a part of a thing's fruits, in favor of one or several persons, either at the same time or one after another, and it can also be limited to run from or to a certain day.
What the law says
Usufruct may be constituted on the whole or a part of the fruits of the thing, in favor of one more persons, simultaneously or successively, and in every case from or to a certain day, purely or conditionally.
Civil Code, Article 564 — Usufruct May Be Partial or Successive. Read the full provision →
A usufruct can cover just part of the fruits
Article 564 opens by saying usufruct may be constituted on the whole or a part of the fruits of the thing. That settles the first half of the question directly: the person creating the usufruct is not required to give away everything the property produces. It can be scoped down to a fraction or a defined portion of the fruits, with the rest remaining outside the arrangement.
Beneficiaries can hold it together or one after another
The same article addresses multiple beneficiaries directly: the usufruct may be granted in favor of one more persons, simultaneously or successively. So a usufruct is not limited to a single beneficiary holding it at once. It can be given to several people who hold it at the same time, or structured so that one beneficiary's usufruct ends and another's begins in sequence — both arrangements are within what the article allows.
It can also be timed or made conditional
Article 564 adds that a usufruct may run in every case from or to a certain day, purely or conditionally. This lets the usufruct be tied to a specific start or end date, or made to depend on a condition being satisfied, rather than existing only as an unconditional arrangement running indefinitely from the moment it is created. Combined with the earlier phrases, this means a usufruct can be shaped quite precisely — partial in scope, shared among several people at once or in sequence, and bounded in time or by condition, all within the same article.
A related point: usufruct over rights, not just things
The article closes with a related extension: it may also be constituted on a right, provided it is not strictly personal or intransmissible. So the flexibility Article 564 describes is not limited to physical property producing fruits — a usufruct can also be built around a right, so long as that right is not one the law treats as strictly personal to its holder or incapable of being passed on.