Text: also on the island of djurgarden is the unbeatable vasa museum, home to the world's only complete 17th century ship.

Correct capitalization: Also on the island of Djurgarden is the unbeatable Vasa Museum, home to the world's only complete 17th century ship.

Text: there is a possibility that some add-ons won't be ready when firefox 57 hits, but that they will be released at a later point in time.

Correct capitalization: There is a possibility that some add-ons won't be ready when Firefox 57 hits, but that they will be released at a later point in time.

Text: of eu citizens play sport at least once a week.

Correct capitalization: of EU citizens play sport at least once a week.

Text: fortunately there is a facsimile reprint from 1863, which seems to be reliable (see external link).

Correct capitalization:
Fortunately there is a facsimile reprint from 1863, which seems to be reliable (see external link).