Shoe trees, yes. I don't see any reason not to.
For conditioning shell cordovan service boots I'll be using Venetian shoe cream. Haven't yet felt any need to apply it to my Viberg's but I've liked it on other shell cordovan shoes & leather goods, so that's what I'll be using for them.
For buffalo rough-out I use suede spray to add a little bit of more water resistance. I don't want to wax them as I've already got other rough-out boots that I've "dubbed".