1. For localizations, I feel like they should be as close to the original as possible, I feel like even changing the small things will lead to bigger changes so should be kept as close as possible.
2. When I first started I got a bunch of the all ages versions of VNs on steam and then found out that they censored a lot of stuff and even messed up routes such as in If My Heart had Wings. Now, I do not buy from any company that censors for western audiences. Censor=No buy
3. I have not watched too many anime that I have played the VNs for so no real opinion here.
4. I have so far avoided VNs with any gameplay, to me that makes them not VNs. When I play a VN I want a story where I can just scroll and read.
Edit: There have been a few anime that have VNs and generally they go with the route that sucks the most aka canvas 2 would never do the route they went with unless required to.
5. Can't really say I know which ones a highly rated other than a couple you mention which I have not read.