No one's forcing you to believe anything, but I'd just like to explain some things further:
1) Despite how vague a reference it might receive in Chrono Trigger, the gang actually doesn't even consider that Lavos created the gates to be an actual possibility. Er, as I was saying, despite how vague a reference the Entity receives, if it actually does what they believe it does, it has a much greater role in CT. The role may be fairly behind-the-scenes, but it doesn't do extremely much in CC other than pull Dinopolis in from the Reptite-dominated timeline. The rest of the "guidance" present in CC is mostly Schala reaching out to Serge from behind the mask of the Time Devourer. The reason the Entity seems to act "dumb" is actually because it barely acts at all; at the end of CT, Lucca says that she feels the Entity has been put to rest, and for the most part, it has. The threat it originally felt is gone, and if it did manage to sense any threat in the Time Devourer, it was likely much weaker, considering that the original Lavos had been in the Entity/planet's core, while the Time Devourer is merely floating around in the Tesseract. This is why Schala, not the Entity, is the one that steps forth and starts Serge on his journey to destroy the Devourer. Also, it is unlikely that Lavos would create the Gates that we use in the game simply because of the fact that, as you point out in your second note, it would be disadvantageous to him. Why would he create Gates that allowed someone to bring about his downfall? And if he didn't create them on purpose, as we have shown, it is doubtful that they would remain active, constant, and in the same location. Thus, it is sensible that even if Lavos could create the Gates, he did not.
2) It is uncertain whether the Entity nudged Crono through the first Gate and on the way to destroying Lavos because he was the Chrono Trigger, or if he was made the Chrono Trigger when the Entity sensed him (this is also debated about Serge, although the circumstances are slightly different). See, Crono's uniqueness is explained; he is one of two Chrono Triggers seen throughout the series, a special status that is more obvious within Serge during Cross than we actually see happening with Crono in Trigger. It is either proven or believed that this is the only reason Crono was able to be revived; otherwise, the Time Egg would not have worked. Also, even if Lavos had created the gates, the group would still not be nearly as ragtag as you might think, and the whole journey would still be improbably coincidental. Marle must be who she is to have the Pendant, to disappear and have Crono and Lucca meet Frog in 600 A.D., and to have Crono end up being jailed, while he, Lucca, and Marle run into the gate for 2300 A.D. when they try to escape. Lucca, well, she's smarter than anyone else could have been about the Time Gates. Frog, while not necessarily needing to be a Frog, must be the Hero destined to wear the Hero's Medal and weild the Masamune against Magus to begin the sequence leading up to the group's arrival in 12000 A.D. Robo, well, he's one of the less important ones, but it's doubtful anyone else could have helped the gang get access to the other gate in 2300 A.D. Ayla has to be the chief to own the Dreamstone, and to fight Azala, who explains a bit more about Lavos. Magus, of course, is the one who the gang is driven throughout the entire first half of the game to stop, allowing them to discover what Lavos really is, and is quite valuable in destroying Lavos. So, you see, whether or not Crono is nudged out the door by the Entity, the whole thing is still destined.
FYI, Crono is the main character of Chrono Trigger. Chrono is the name of the series.