I have two somewhat stupid questions I hope someone could help me with? I just want to make sure I am getting the best value from my training. Apologies for the wording but I am not an experienced cyclist.

I am using an interactive trainer (Elite Novo Smart) and Trainerroad.

1. Bike gears
I previously trained using the Trainerroad app with the chain on my big sprocket (front) and middle to small cogs at the rear cassette. A few months ago when I got a new phone and installed trainerroad again, I noticed the tip to use the small sprocket (front) for less noise and less stress on the chain. I have done this and it is certainly quieter. However, when I race I use the big sprocket (front) and the smaller sprockets (back cassette) so my question is should I be using the big sprocket with the app to make gains? I use erg mode so allow the trainer to control resistance but obviously when I use the big front sprocket my bike computer shows me holding a much higher speed and bigger distance covered. I suppose I am asking is: when using Trainerroad and the smart trainer, does resistance I use when using the small front sprocket equal the resistance of using the big front sprocket? Any advice would be appreciated.

2. Training Plans
I trained using the low-volume sprint triathlon plan for most of the year and made great progress (again from a beginner perspective). My life does not allow for much more training time so the mid-volume sprint plan is too far a stretch. Because of this, I started using the Olympic distance low-volume training plan as the training sessions are roughly the same number as the low volume sprint albeit a little longer for each with more time involved for each session. Still manageable though. My questions is...are the low volume sprint and low volume Olympic similar enough to allow me to progress and race fast at sprint events?

Thanks for your help,
Karl