Yeah I'd say the Royal Library barely affects culture victory. It adds a few more great works of writing slots, which are the most common, and nothing else towards tourism. The main use of the Royal Library is for more XP.
"Burial Tomb" is the egyptian temple and quite usefull when going wide and religious. It cost no upkeep and provides + 2 happyness + 2 faith.
By taking 3 policies in piety, the building can be built at double speed and it will give + 3 faith and +25% Gold.
It can be later enhanced by a religious belief to give +2 culture if the city has 5 followers. (It always depends on what other beliefs are still available if +2 culture is a good choice.)
-> build at double speed, +2 happiness, +3 faith, +2 culture, +25% Gold, no upkeep.