Translation:Do you like to travel often?
Adding the a ti puts the emphasis on the you. Just like including the tú in ¿Tú bebiste toda la leche?
So is it similar to asking 'And YOU, do you like travelling often?' in typical English conversation?
No, it isn't, but often is there. It's one of those quirks of Spanish.
Nope, not really. Of course, I'm not fluent enough to tell you when exactly a native speaker would include it.
Is gusta is the only word that requires "a ti te, a mi me, a usted le, etc" in front of it? Seems to be most of the examples provided so far
Again, I don't see the need for "a ti". Is just "te gusta" also acceptable?
Yes. The "a ti" is emphatic. It's also common enough that duo would be doing a disservice for not including it.
How would one ask whether you often like to travel, as opposed to liking to travel often? In other words, how would one ask whether you frequently like to travel (at all) rather than whether you like to travel as often as you do? Would one ask, "¿A ti a menudo te gusta viajar?" I'm trying to get the adverbial phrase "a menudo" to modify the liking instead of the traveling.