No it is struct of floats, you can see it it’s API refrence:
It probably wont harm if you use integers only, but there always possibility CPU might butcher they key during processing by adding some odd fraction making value hard to access without looping
There different type which has vector made of integers called FIntVector, but not sure if you can use it in Blueprints, you can try to find it, but oyu can definitely make more stable map with it in C++:
It would be hard to do graphical related stuff in vector of integers.
I also notice there being new template implemented TVector allowing you to create any vector type with as much of dimensions you desire