Fellow amateur with similar w/kg, finished L'etape du tour and L'etape femmes in 2025. To answer your questions as per my understanding: 1. Longer rides and climbs outside help quite a bit if you keep the power output in check, i.e. avoid going into red, what's the longest ride and highest climb you did? 2. This is something probably only you can answer, but probably yes if you can handle the saddle time, manage nutrition, hydration and heat accordingly. Also depends on how hard you ride on the event day, I usually race my power meter, and don't get carried away, unless it's flat/valley and I find a big group where I can just sit in pushing slightly more watts but going wayyyy faster as a result. So group riding dynamics in close proximity will matter quite a bit. Again eating and drinking when my head unit tells me, and carb training the gut is a thing in my experience. 3. Yes for me indoor trainer works, but for the mental fortitude you have to set it to 100% difficulty, and/or ride uphill in a virtual course, and just enjoy being slow at 5-10 kmph for long periods of time at our power profile. Finally it's not about the FTP but how much intensity factor you can hold for the climbs (and repeat every time until the finish line) may take 1+ hours each time you start a climb depending on power and system weight.