In the new V, Diana shows up as Anna's mother, right? So is this new version supposed to be taking place 20+ years after the original or is it just a completely different interpretation and they just reinvented Diana?

Diana in The New "V" is not the same Diana as in the Original "V"

i think it is set 16 years after the oringinal v for the following reason
1.diana is in priosn for 15 yrs the oringnal 16yrs ago
2. v`s have been here before
3. diana in the oringinal read the bibble and the human soul so dose the new one
4.the storyline over making human/alien babies!how do they know it would work?where did they come up with idea come from?

i bet you a bottle of whiskley at the end of season 2 the cliffhnager will be that it is part of the oringnal