Well certainly whenever I searched imperial cutter on youtube, people don't seem to have anything bad to say about it!
I fly a Cutter & it is overall a fantastic ship. To make it a pleasure to fly though, which mine certainly is, you need 3 things; a G5 Charge Enhanced 7A Power Distributor, a G5 Dirty Drive 8A Thrusters, & the ability to turn around by switching Flight Assist off (make sure to turn off the audio notification under options). Once you've cracked the latter it is utterly amazing, you can do power slides in the thing! Here is my Cutter's current set up (I haven't done the Engineering info but the power & thermals etc do add up after engineering):
https://eddp.co/u/GGZ4v7hW
Do Data and Passenger missions both count towards the total of 20 ? or is it 20 a piece? Do there tend to be passenger missions to the same destination as the data missions?
Yes. It's 20 missions regardless of type.
Depends up on the layout of the local galaxy; sometimes yes, sometimes no. Type Thanatos into the Galaxy Map. Look at the layout of that system; you could sale between both those large stations collecting passengers until full - no need to board hop. Look around the Imperial Capital at Achenar for similar systems, Cemiess might be a good one but you may need to skip the stations near Cemiess A unless you got good thrusters as the gravity would slow you down - you could probably just sale between Mackenzie Relay & Titius Station and pick up passengers to a couple of destinations.
Be careful when doing Rep+++ passenger missions as they can often be illegal passengers and if you're scanned in and out of stations - zap, zap BOOM!
If he just does the normal folk, ie the ones without the crown, he won't encounter any of those.