1) Yes, I like
Eva, though I prefer
Eve.
2) Yes, I prefer
Eva over
Ava, mostly because
Ava is so ubiquitous.
3)
Eva goes well enough with
Sophia, though the two are a little rhymey together.
4) I think it depends on how you're pronouncing
Eva. If it's "EVE-A," then I think it goes better with
Sophia. If it's more like "EHYV-A," then I think it goes better with
Sofia.