With MP libs, will all dependencies have to match compiler versions? or are there just certain incompatibilities between some versions of the compiler? I have had some compile time errors due to my compiler version not matching the compiler version of the library.

Versions don't have to be exact but there are some current incompatabilities with older versions of kotlin if the libary hasn't updated in a while (I think this mostly has to do with the gradle meta data being experimental and not on by default)

Current Kotlin/Native has rather strict compatibility rules, so generally 1.3.3x is compatible, while 1.3.40, for example, will not