um....There's no strict rules especially these years with the rising of net-language (or should I say, Chinese leet talking? kidding...)
哦 é/ó/ò
"é" is not an interjection
"ó" : indicate suspicion/doubt/query, mostly as replying to a statement or a question. 哦?
"ò" : usually in a soft, gentle falling tone. it can be used to express approval/(sudden) understanding/surprise or whatever.
Actually there's a lot of "informal" uses of "o" that are not listed in dictionaries but for now I'll leave them there.....
喔 ō/ò/wō
"ō" not very often used. express understanding -- personally I think it has some excitement factors involved, but I'm no linguist....
"ò" it's the same as "哦(ò)", but personally I think it reads louder and sometimes is used to express an appalling feeling.
"wō" this is the "cuckoo-doodle-do" in Chinese. "喔喔喔" sometimes with "——" in them. And you can pronouce them either "wō" or "ō" -- no strict rules!
"喔" is also often used as "ouch", as well as "噢", while "哦" seems less popular in this sense.
my dictionary says "噢" is the same as "喔(ō)" but personally I find it a more exciting/stressing form of "哦(ò)". Again there is no strict rules.
嚄 huō/huò/ŏ
"huō/huò" : indicates excitement/surprise/appallment
I think "嚯" has the same use
"ŏ" : same meaning. Actually people use "哦/噢/喔" for all the "o"s and I don't think most people know this!
迲 qù: I don't think it's popular anymore. We simply use "去" to express the same feeling :"nonsense!" "off you go!", or to scorn/disdain/ignore the opponent.
also there are "qiè" and "què"s that can be used in same way. There are no set characters so most often we use the character "切".
There are so many others....like 咄(duō)! (hey, it can even function like "duh!/d'oh!"), 哈(hà, which is generally the same thing as "ha"), not to mention all those "a"s.....
I won't expect a "complete list" to be honest....