Adding Fiber to internal network at work - I'm a software/mathematics guy looking for advice

Ducting is to be laid for fiber and I am being tasked with choosing fiber, media converters and switches. I am familiar with fiber in that I studied lasers from an applied math/physics perspective, setup free space optics experiments for single and two mode lasers in research lab with a single fiber cable (SIMPLEX I think is how it is called in networking) but I have not worked with end-user equipment in this regard. I have extended part of the existing network to other buildings < 100m and I have set up routers/APs/virtual machines/firewalls/VPN etc and am a linux user (if relevant).

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The new building will have 5+ fibre connections coming to it from around the site so I am looking for advice with fiber types and then converting to RJ45. The fiber will run outside in buried ducting and we are looking for a consultant to terminate the fiber ends correctly (I am reluctant to terminate the ends myself and have said so). My known constraints/issues are:

1. Fiber running outside for 100s of meters (but under 1km)
2. 5-6 fiber (one per building) connections coming back to one room/switch
3. I do not want to get locked in to a particular/single manufacturer if possible to avoid having to buy proprietary patch leads or something anytime I want to add a device to the network.
4. The longest length of the site appears to be ~400m (corner to corner)

I've read a few posts including https://www.reddit.com/r/networking/comments/3gx5dz/ysk_if_you_dont_about_fiber_optics_and_how_they/. Looking around individual media convertors seem to have a few comments saying to avoid them, mainly due to if another person takes over managing the network they may not find the converters etc. I am looking for a rack mountable, multi port cable media convertor. My thinking is if it's rack mountable it will be seen and we can label it. My google search has found this:

http://www.ot-systems.com/en-ww/product/detail.php?MID3=4&SID=87

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From the image I naively assumed it worked as 8 individual media convertors (fiber in and the next adjacent RJ45 out), but I am interpreting the applications image to suggest the device is smarter and I do not need to take pairs (unless I am reading it wrong). Either way using 1 or 6 patch panel leads (one for each fiber in) to connect the media convertor to the switch is not an issue. However, the fiber connection is SFP and from my reading I do not think this restricts the types of fiber I can use but I am unsure.

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So my uncertainties and unanswered questions are:

1. Do I need simplex or duplex fiber? Does it matter these days?
2. Can I arbitrarily use either SIMPLEX or DUPLEX with the above media convertor?
3. For multiple fiber cables coming in is the media convertor above suitable? Are there better recommendations?

I will need media convertors at each other building but they only need a single media convertor.