Probably when the next planet gets released, though if the alternate starter planet is created we might have to wait awhile for the next level (As in till the second half of next year).
Ten main story planets per playthrough. Not all players will visit the same ten planets because multiple choices of probe planets will eventually be available. There will be more options for early planet choices than for later ones.
Planets like Uveto, which do not have probes, are considered side planets and do not contribute to main story progression or to raising the level cap.
LvL 9 MAY but MAY NOT be added after Uveto will be done as it was I think intended for lvl 7-9 PC's. With next probe been not on typical planet it may not include adding more lvl's but as usual future is still everchanging xD