srw
It's a bit more complicated than that...
...on the top, with lycra shorts on the bottom. Some of us went the whole hog - in the drizzle - and rode to Southend in woollen dress trousers too.
Anyway - others have covered the gearing. For what it's worth, I'm quite happy with what I believe (but have never investigated) is the standard 3-speed gearing. Looking at a recent gps profile (StuartG will know which hill I'm referring to), I was quite happy with a climb of 150 ft inside half a mile, typically at 5% gradient, seated. The short sharp section at the bottom that was typically 8% gradient had me honking out of the saddle. I've never Ditchlinged on the Brompton.
Your weight won't be a problem - compared with me you're a slim whippersnapper. At my heaviest I was more than 25% heavier than you are. The only problem I ever had was a seatpost eventually becoming distorted - which took several years of daily riding.
Personally I've gone for the hub dynamo (never the bottle dynamo, which is a nasty waste of money). It's an easy retrofit and makes the bike a perfect commuter job.
I suspect (my current bike is pre-modern suspension) that I've got the softer suspension. It makes not a jot of difference - if you're heavy you simply squish the rubber further.