Is it true that if you know Latin, it's easier to learn the Romance languages?

Yes greek and latin are the foundation languages.

Your theory is a known fact. :)

Not only do Romance languages share a good proportion of basic vocabulary—still recognizably the same in spite of some phonological changes—and a number of similar grammatical forms, they can be traced back, with but few breaks in continuity, to the language of the Roman Empire, Latin.

Yes, and vice versa.

Yes, except French, because screw that language and all of it’s silent letters that nobody pronounces so it’s completely impossible to hear a sentence and know how to spell it without memorizing the exact spelling (and gender) of every word.

@gorillapaws I did dictees with my last French tutor. An interesting exercise!

factum

Yes.

In a sense, Latin is to the Romance languages as Old English is to English (except the affinity is even closer—English has shed much of its Germanic vocabulary in favor of Latinate borrowings and Old English can appear quite foreign to the modern English speaker). Vulgar Latin, as spoken across Europe in Late Antiquity, is the direct predecessor of the modern Romance languages of Italian, French, Spanish; they are, in linguistic terms, the daughters of Latin. Knowing Latin is helpful to learning the Romance languages and can also help with improving one’s English vocabulary (in terms of better understanding the origin of English’s many Latinate words).

Of course it’s true. Pick a romance word and check the etymology of that word.
Have you seen Akelaa and the Bee? Very informational.

To a much smaller degree, knowing English helps in learning a Romance language, since English shares many Latin roots.

I say yes and no. In learning to spell and write and read it probably would helps since many of the root words come from latin. But when it comes to knowing what word you hear pronounced when someone is speaking to you, it will become tricky since the pronunciation in a lot of romance languages aren’t exact to latin. I know spanish and english and everytime I try to learn french I get tripped up. Some words sound the same but are spelled differently. Like the word codo. In spanish it sounds like ko doe in french coo do. Both spelled the same. In Spanish it means elbow, and in french it means code. In latin its pronounced like spanish but means code, not elbow. So if like me your brain can’t keep track of all the different sounds and multiple meanings it can be confusing.

You are the most fascinating person @Pandora!