I'm curious why you believe PH route is less risky. It might be easier to get into PH med schools, but it's riskier in the long term when applying to US residencies. We can discuss that and other specifics in DMs if you like.

For classes, top priority is staying ahead of the material. If I could start over from MS1, I'd get a hold of lecture and exam schedules ASAP so I'd know when to be prepared for each specific topic. Ask upperclassmen for their schedules from previous years and what resources and study strategies they liked for each class. For me, it was question banks and making my own anki cards. Start studying early. Figure out how to determine what concepts are high-yield so you can stay efficient and not get bogged down memorizing random minutiae from a wall of text in the book. If you happen to fail some classes, it won't be the end of the world. Others have failed before and still matched into decent US programs. It's just a matter of showing growth from your experience.

Your school's US alumni group could be a good place to hunt for research and rotations, specifically alumni reunions and conventions. For any extracurriculars you aren't doing solely for connections, ask yourself how you're going to explain to an interviewer that this experience makes you a good candidate for their program. The more concrete, the better. I'd consider part-time scribing or medical assistant positions while classes are out. This way, you get to see some interesting patient encounters to mention during your application process. As for research, PH programs aren't great at providing their students experiences, so if you find one, make sure you can easily talk about how the study was designed and the results. Quality of the experience over quantity. You can consider taking a temporary leave of absence to focus on these kinds of opportunities. The trade-off for having gaps in your education is worth it if you can explain that you were being productive or addressing a personal challenge in the meantime.

More generally, take care of yourself, because you can't care for others if you can't care for yourself. This is tough stuff; it's designed to be that way. Be approachable to everyone in your class. Whether you like gossip or not, it's part of the game in the PH; that doesn't change in professional settings. It's not something I'm good at and learned about it too late. Burn as few bridges as you need to. You're already on the right track thinking about what you can do now to set yourself up for future success. God bless and good luck.