Citing full names of authors
No, you shouldn't change your bibtex database every time. Bibtex converts automatically from its native format "Surname, Firstname I. and Other, Author" to whatever the journal style is (for instance: F Surname, A Other), as long as you have full names in the database. Name formatting is something that people often get wrong at first when they have little experience with bibtex.

So you should aim for having full names in the database, at least for those papers that you need to cite with an unabbreviated first name. Everything would be easier if all journals used initials, but it's a tough world.

I suggest initials for theses, preprints and submissions, and only switch to full names after the article is accepted in a journal that demands them (and after being asked by a copy-editor that demands them). This is the solution that minimizes the workload on the author.