1) The big question here is not superstition, but greed. Of course, we can choose to wish people with something better, like spiritual good or giving them a blessing instead. However, having said that, wishing people prosperity in the church is not necessarily bad, because there is now an understanding that we can preface it to mean spiritual prosperity. Many people I know today would add 「主寵日隆」.
2) Now, this one sounds like superstition to me. The word 「福」 is definitely not evil. As to the other ones, they are of course secular. But there are also Catholic ones out there, that I know many churches have available. Get those ones instead. 「福」 simply means beatitude. We can christianize it, since we also have the Beatitudes.
3) For fun, yes, they are quite harmless. But not the same can be said about horoscopes or other future reading media like palm reading etc.