nDman

Fujica ad in magazine of 1960 ... the father of the X-Pro2

Hey! 
In August I was travelling through Portugal for good 3 weeks with my recently acquired Fuji X-T20 and the Fuji 14mm F2.8, Fuji 23mm F2.0 and the Fuji 56mm F1.2. Hope you enjoy the photos 
 
1.Faro
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Just sharing some pics from a walkabout in Barcelona last year. I had the 14mm, 23mm 1.4 and Zeiss 50, but I ended up using the 14mm the most. Some of my favourites (straight from camera JPEGs)
 
 
Fuji X-T10 | XF14mm | 1/550s at f8 | ISO 800

 
 
Fuji X-T10 | XF14mm | 1/680s at f8 | ISO 400

 
Fuji X-T10 | XF14mm | 1/900s at f8 | ISO 200

 
Fuji X-T10 | XF14mm | 2s at f6.4 | ISO 400

 
Fuji X-T10 | XF14mm | 2s at f5 | ISO 1000

 
 

Wut?!   Once upon a time there was a fanboy post about XF 14mm titled "The best Leica lens Fuji ever made" or something like that… still true. Tack sharp, very clever construction (you don't have to worry about vignetting and internal reflections with filters), light and fast. Love this little gem.
 

(X-T1, XF 14mm, 26 seconds from tripod; air temperature is around -22F)

A few more..

Love my 14mm - 21mm of quality!!

Not a Fuji user, but I'll chime in.
 
"Where I live there aren't any places which rent out fujinon lenses."
You are deciding between focal lengths, just rent a camera and a lens from any brand.
 
"If I'm gonna invest in a new lens I have to be 100% sure I won't regret it."
Given that you are not familiar with the relative FOVs, that's not going to happen. If you are that worried, the best solution would be the 10-24 zoom.

What follows is subjective, although most people I know are in agreement.
16mm is actually not that wide, especially when it comes to tighter interiors. The speed will be mostly irrelevant for the purposes you mention, unless you take night shots - stars, auroras etc. It is roughly as big, as heavy and as expensive as the 10-24 zoom. So, you better be sure that you need that speed. It is also weather sealed, but depending on how and what you shoot, that might be completely irrelevant.
14mm is great. It is in the beginning of the ultrawide territory, without being an extreme. It is a nice compact lens, easy to carry around. It also has the smallest filter thread of all of the lenses you mentioned, which will result in cheaper filters in case you decide to use those.
12mm is getting really wide. It is great for tight interiors and landscape, but that wide becomes a bit strange for city shots. One can achieve very interesting results, but it will be of limited use. 
The 10-24 zoom is also very nice, although I doubt the usefulness of the OIS. It is nice to have, but at these focal lengths it won't give you as much. The manual focus is fly by wire, which I find to be a big problem for landscape. It also has the largest filter thread.

Personally, I would take the 14mm. 

in the dark by Jörg Staudt, auf Flickr
 
X-E1 with XF18-55

monochrom by Jörg Staudt, auf Flickr
 
X-E1 with XF27 f2.8

Fujifilm X-T1 & Fujinon XF 23 mm f/1.4 R (1/420 Sec., f/7.1, ISO 200)
 

x-t1 and 18-55mm.  b&w conversion in lightroom.

Yes, you can use the 199A on Fujifilm cameras.
 
In fact, you can utilize the 199A's on board auto circuitry to adjust it's own lighting. Just set the settings to reflect your camera's or vice versa. Some fine adjustments are required of course.
 
The 199A's flash temperature is slightly lower / warmer than modern speedlights so, you need to keep that in mind.
 
And oh yes.....the recycle time......