Hyperlinks are character-styled Internet Link (and Visited Internet Link). You should check configuration of these character styles to see if font colour has been set to white or transparency to 100%.
Page borders are configured in page styles. Check your various page styles.
Formatting is predictable when no direct formatting is present in your document. This depends on your skills, knowledge of ODF principles (the are in principle the same in OpenOffice and LibreOffice but the latter one has better maintenance) and previous routine(s). Please attach a 1- or 2-page sample file so that I can have a look.
When converting a document, tak advantage of feed-back features by enabling in
View menu: Formatting Marks, Text Boundaries, Table Boundaries, Images & Charts, Show Whitespace, Field Shadings. You can leave them always enabled because they provide very valuable information and visual clues never print.