At some point when people have been on diet a long time, it's a compromise to keep you going longer without getting depleted. It is of course, my preference for people to lose the tactics that don't work a little sooner and thus avoid the prenatal but I do eventually recommend them. :)
It's enough. I won't go into the history of iodine deficiency and public health, but it's enough. If you want to add in shellfish too - I am fine with all pink swayers having that one-two times per week.
I personally believe Vit. D is a big blue swayer, but the thing is, after this point you've been on diet soooo long you probably need it. 3 times a week is not daily. :)
Folate is better if you can get it. The reason I do not blanket prescribe it, is that a lot of people can't afford folate and thus will end up taking nothing. Since most people do great on folic acid, I think it's best to continue to recommend that for eveyrone except those with MTHFR. That doesn't mean folate is not better - it is (probably LOL)