With the Gates belt drive, you're not going have as many maintenance issues as a chain driven bike.
That said, the LaFree +1 doesn't have quick release, so if you think you might need to replace the tube in the field (I always try using the cheap but excellent Park GP-2 self-adhesive patch kit first, and have had great success), then you'll need either an adjustable wrench or a metric wrench of the proper size (might be 15mm, but check!) in order to remove the wheel. Since this is a Gates drive (interesting that the
Giant site calls it "Gatex") with an IGH (internally geared hub), you'll want to learn and practice the procedure for removing the rear wheel at home before attempting it in the field. Gates has a video
here, but
this video shows the procedure with the same hub as the LaFree +1.
Summary:
Multi-Tool: Doesn't have to be a fully fledged unit (no chain tool, for instance). Mostly for the hex and/or torx bolts.
Tire irons: Light plastic ones are almost always fine.
Metric
wrench: for the wheel nuts
Pump: TaraBara's suggestion for a CO2 kit is reasonable, but be sure you carry enough cylinders for a tire of that size (and maybe twice as many in case you get 2 flats!), and again try using it at home so you're not figuring it out for the first time in the field. I personally like the "Micro Floor Drive" pumps from
Lezyne. They make a number of versions - you'll want the High Volume (or "HV") version, and I would opt for the built-in pressure gauge. These have a fold-out foot with decent length hose, so you can pump as much volume/pressure as you want pretty easily - just a shorter stroke than a full size pump. These light enough to carry on analog bikes, but a tad bulky for the frame mount. For an e-bike with a built-in rack they're easy to carry. I really like the way the Lezyne pump heads screw onto the valves. I use their digital floor pump at home, and have a tiny hand pump with hose for my analog road bike.
Wet wipes: Just a small pouch with wet wipes to clean your hands after any repairs.
First-aid kit: This can be as small as a couple bandages with ointment if you travel in town, but off-road you'll want something more extensive since you might be miles from a drugstore.