Minsk is certainly one of the easiest places to spot locomotives. There will always always be at least one locomotive hauled train in the station. You wont have to wait long to see them.
The best time of the day for spotting locomotives is around 06:00 to 10:00 and around 20:00 to 00:00 as that is when the majority of long distance trains to and from Russia arrive and depart. But there are others all throughout the day. There are approximately 30 locomotive hauled trains a day at Minsk station.
Another place i recommend going is Stolichny which is one stop five minute journey from Minsk on a suburban train. This is where a massive freight sorting yard is located and also one of the locomotive depots. There is always lots of interesting stuff parked up around there and you can get a good view from one of the road bridges that crosses over it.
Another site i recommend for Belarus railways (and for Russia railways too) is yandex which has a very simple easy to use departure board for any station.
Minsk Station (All Trains):
Найдётся всё
t.rasp.yandex.ru
Minsk Station (Long Distance Trains):
Найдётся всё
t.rasp.yandex.ru
Minsk Station (Short Distance Trains):
Найдётся всё
t.rasp.yandex.ru
Again this is only for passenger trains and unfortunately nothing for freight or empty stock workings exists.
Also note that a small amount of trains (mainly suburban trains) leave from the separate Institute Of Culture station which is located a short walk away behind the main Minsk central station.
Yes but the FCDO love unnecessarily advising against travel to so many places. If you listen to their advice then you will have to avoid half the world.
I will say that i have visited both Belarus and Russia earlier this year and again last year without issue. I went to Smolensk in Russia earlier this year and stopped off in Minsk in Belarus for a couple days on my way there. Everything is normal. You would not even know that anything has changed except for a few western brands dissapearing. It is not a warzone. It is not like you are going to Sudan or Somalia or somewhere like that.
British travel insurance might not be valid in Belarus but many people dont bother with travel insurance anyway. I personally never bother getting travel insurance (except in the few countries where it is required to get a visa) but it is up to each individual if they want to take the risk. There are probably some insurance companies that will cover Belarus still (but it would likely be very expensive and not worth it) but you would have to look around. I personally wouldnt bother.
It is up to up each person but if you listen to the FCDO then you will unneccasarily miss out on a lot of places around the world. Of course some warzones are best avoided but overall their advice is far too extreme.