<p>Can I really and truly trust .NET to initialize fields (like ints, structs and the like)?   And what if I still want to initialize those fields - what could be the repercussions?</p>

Yes, you can really trust .NET to initialize fields to their default values.
There are basically no repercussions for doing it explicitly. (One small caveat here: if you initialize static fields explicitly, then anyone running the type initializer a second time via reflection will end up re-initializing those fields. This is a real corner case though!)
Do whatever promotes the most readability in your particular codebase.