For the 2-string-index-F-chord, if I try to hold my index finger vertical on the B & E strings, it is a hard chord to do because my hand just doesn't flex well into that exact position. I keep my index pad at a slight angle over the strings. There is lots of room in that first fret to find a comfortable position!
On G chords. I've seen people play them different ways, pinky on the G, ring on the G, holding the G & E with pinky & ring, etc. In the end, if you can efficiently make that or any chord using whatever fingers you wish, it is fine. Practicing all positions is best, because there are some progressions, and chord ad libbing that work easier from one position vs. another, and some songs (Pink Floyd comes to mind) just need to have that B & E string held down.
My approach (and I am no expert, but I think lazy sometimes translates to efficiency! :D)) is generally to practice using fewest fingers necessary, to use the position that is most comfortable, and to play using the most efficient position (which is situational).
...so ever since then, I always hang on to the buckle.