Well, back in the day, first and reverse were usually the same sized gear ... not sure about the FR-S.
Your launch technique will come with practice. Meanwhile I suggest you slip the clutch a bit on starting out in both first and reverse. No, it's not going to burn up your clutch unless you over do it.
With an engine that has relatively low torque and a relatively light flywheel, sometimes they need a bit of RPMs to get them moving.....
I know that when I back out of my steep driveway (uphill), I have to ease over the apex (at an angle) where the driveway meets the sidewalk (so I don't scrape) and (of course) the blind spot is just where the traffic could be coming from. So, I have to slip the clutch quite a bit to get out. Been doing it for about 9 months now ... clutch has held up just fine ....
And yes, I've been driving clutched vehicles for over 65 years now and never burnt up a clutch.
humfrz