Using "curious" in the sense of "odd" or "strange" is more British than American. It does still crop up here and there, but is somewhat archaic, formal -- or, in fiction, intended to convey a British and/or old-fashioned kind of person. E.g., 'How curious!' Dorothy said, peering at the bright purple tree.
So absent context, "The curious boy" will be ambiguous. No getting around it. You have to tell whether it's about the boy investigating something ("The curious boy pressed deeper into the forest") or about a boy being odd in some way ("The curious boy walked down the sidewalk, and we all stared at him"). Or if it means both!
This ambiguity will also be used when someone wants to make puns. "What a curious creature you are!" may mean "you are always wanting to investigate" or it may mean "odd." I recall there being some of this double-meaning in Alice in Wonderland.
"He's very curious" will generally be understood to mean someone has the quality of curiosity, not oddness, in modern American English, but if you want to reduce ambiguity, you use "about" to clarify. "He's very curious about everything!" "She's very curious about ancient Egypt." "The neighbors very curious about our business, and I want better curtains in our house!"
In modern American, "curious" people or animals (the curious cat, the curious child) will be "inquisitive" with an ambiguous side-order of "odd"; the more stereotypically inquisitive the animal (or person: the curious neighbor), the more likely the assumption will swing to "inquisitive." But "curious" inanimate objects will always be "odd." And "a curiosity" is an odd thing.
(You wouldn't use "Curious you!" because either way, applying adjectives to pronouns rarely works well. "Red you!" "Angry him!" "Stinky her!" "Inquisitive me!" -- you can get away with it sometimes, in a slangy fashion, but you tend to need a noun, like "Curious George," the monkey who is curious about everything! (The Curious George books are a series of children's books which strongly normalizes "curious" as an adjective meaning "inquisitive.")
So if you want to avoid ambiguity, use "odd" or "peculiar" or "weird" or "fascinating" in American English, to mean those things. And only use "curious" for things like "He's very curious" (inquisitive) or "I'm curious about this sentence here" (I want to understand this sentence better, I am interested in this sentence).
The word vacational doesn't exist in any Dictionary. Nor do we find it in any Grammar book.
Like many other nouns used as adjectives, the noun "vacation" can be used as an adjective. For examples:
Shimla is a beautiful vacation spot.
My parents are trying to buy a vacation home in Darjeeling.
I have got a vacation job.
We don't have any vacation days left.
Vacation season hasn't set in yet.
I think we can also say "Vacation Studies English Language School".
To sum up, when we usually use 'vacation' as an adjective, there's no point in using 'vacational' that doesn't exist or is rarely used.
Best Answer
Both 'or so' and '-odd' can mean either a little more or a little less. If you want the number X to be understood to be the smallest approximate number, you might use "at least X" or "X or more" or "more than X".
If you are certain you won't arrive before 8 o'clock, you should say so directly. Otherwise, we would just say "around 8 o'clock, but I might be a little late." with the understanding that if we are lucky and don't have to stop at too many traffic lights, we might show up at 7:55.
If the number were much higher than 10, we would expect you to say "I have read more than 40 books." or "I have read about 100 books on Chinese history."
Similar to the second example, if you thought she could be a lot older than 40, you might say "She looks around 50 years old." meaning maybe 48 or maybe 52.
I personally find the -odd suffix difficult to use. It always seems better to me to say "about 5 things" instead of "5-odd things". Usually I don't use it with a specific number. I might say for example,
That would mean it has been at least a week and a few days more. If I hear other folks use it in conversation, it doesn't strange to me at all, so don't think I'm telling you not to use the -odd suffix. I would just take someone else's advice on how to use it naturally in your examples.