Reddit mentions of Richard Hakluyt and Travel Writing in Early Modern Europe (Hakluyt Society, Extra Series)

There really isn't a papertrail for Marlowe - no library, no manuscripts (produce one and I will swoon) and no extant letters. This is not really all that uncommon - the loss of material is one of the biggest impediments to study, and it is hardly surprising considering the length of time which has elapsed. It is certainly not suspicious.

De Vere has far more surviving material by virtue of being an aristocrat, not by virtue of having written Shakespeare's work (things are much more easily kept when you have a large ancestral home).

As for pronunciation - David Crystal has done some really quite interesting work on 'restoring' Shakespeare's accent to his work, I thoroughly recommend you take a look.

I don't find anonymity to be particularly surprising for this period - authorship is not usually the first concern of the early modern reader, unless the author had become known 'in real life' so to speak. Broad examination of frontispieces to printed plays in this period suggests that information like the acting company or theatre where the play was performed took precedence over the author's name in many cases. For example, the first edition of Marlowe's Tamburlaine has no author identified. Especially considering that it is unlikely that the writer themselves who brought the work to print, anonymity is almost expected.

Also: travel writing was totally a thing in early modern England.