1. You're totally right regarding catching cancer early, but
pancreatic cancer is diagnosed really late because it takes more time for symptoms to show. (By the time you feel it and go to the hospital, you're waaaaay past saveable)
That being said though, I agree with you that it would have been more interesting for Sator to be caught between a rock and a hard place in that he controls inversion in the future but also in that future ravaged by climate change the support structure for modern medicine has broken down and he needs to risk coming back for something like gene-therapy, and when this too fails it's what leads him to opt for suicide 'in his happiest moment' and ultimately inadvertently threatens the spacetime continuum. This fits more with the determinism/free will theme. It's a huge dropping-of-the-ball from Nolan and a big 'win' for the "guys guys Nolan isn't as smart as the acolytes think' camp. Hope that answers your question about the pancreatic cancer thing: yes currently it's all pretty treatable if you catch it early but pancreatic is caught really really really late and that's very likely why Nolan chose it.
2. Also, no, you can't travel forward (or backwards, for that matter) faster than 'real-time'
within the movie's logic.
Even when you go "back", you're going back 'in real time'; AKA it'd take you forty years to go back forty years in real time. (IIRC when they invert inverted-bullet-wounded Kat and go to the airport (again) to re-invert, they plan it so that a few days elapse in 'backwards time' so she can heal) That's how the future Sator is sending himself inverted bullets, for example. He's burying notes saying: "Give me inverted munitions here in this spot" and many years in the future, the older Sator (who remembers himself making that request, like JDW remembers giving Kat the 'leave me a distress call anytime' message) is burying inverted munitions (sixty-year old bullets, for example) in that spot, upon which they slowly trickle back through time and arrive 'right away' (and in six-month old practically new condition) for past Sator.
DONT ASK HOW FUTURE SATOR IS ALIVE IN THE FUTURE WHEN APPARENTLY ACCORDING TO THE MOVIE HE KILLS HIMSELF NOT TOO FAR FROM NOW (YES WE KNOW IT MIGHT NOT BE SATOR HIMSELF ACTING IN THE FUTURE BUT THE MOVIE CLAIMS IT IS)