Welcome aboard

The 2010-2022 models come with one remote Kipass Fob and one passive RFID card (credit card sized, sounds like the "backup fob" that is under your seat).
The early (08/09) models came with 2 Kipass Fobs.
If you lose all of the Fobs/RFID cards then you will have to replace the Kipass computer as well as at least one Fob/RFID.
Ed Ramberger does cheap clones of the RFID cards if you want more, but unless you are the kind of person who regularly loses such things, there is no need.
My Fob lives in my riding jacket in a small ziplock bag and only comes out when the battery needs replacing (about every 5 years).
My spare fob has never been used and is securely stored at home with the battery removed.
The ignition key (Stove knob) lives in the dash and is only removed to open the gas cap or side-bags.
Most of us get a normal key cut so we can open the gas cap and the side-bags without having to remove the Stove knob.
Only in North America does the maintenance plan require a valve check at 15k miles. In the rest of the world that is at 25k miles, and every 25k miles after that.
It is a quite expensive service so budget $800-$1000 for that. The in between services are $250 as just oil, oil filter and final drive oil change. These are easy to do yourself if you have minimal mechanical skills.
The 2015 has a slightly lower 1st gear ratio, has better Linked Brakes, a different windshield with an openable vent, and a slightly different saddle.
If you are not likely to push it hard, then there is very little practical difference.
Colour is a personal choice. Mine is black (I had a choice of black or grey in 2007) but I would like to get a lime green one one day. The blue also looks good.
You can download an Owners Manual from various sites online (just Google it) that explains how the Fobs & RFID cards work as well as the rest of the bike.
They are worth a read if you are considering buying one.