Kanji came from China originally as Japan didn't have it's own writing system. It makes it much easier to learn Japanese if you're Chinese because you fairly much know the kanji already and just need to learn how to say them and learn the word exceptions (Around 80% identical or something like that even after all this time).
The small "tsu" doubles the consonant that comes after it. The Tips section for Hiragana 4 talks about the small tsu: https://www.duolingo.com/skill/ja/Hiragana-4/tips-and-notes
That means that you are the outside. You can think about the correction of phrases like that by removing the 私は from it and then seeing the result. 外です would mean "it is the outside" weirdly enough. You need the location particle に. 外にいます would then mean I am outside. EDIT: Notice that it's no longer です as that conjugation is to be used without a particle (thanks to IsolaCiao, see his reply below for further details) Meaning that you are in the outside which in spoken English is I am outside. The 私は is mostly ommited and derived from context for sentences this simple
You're right that 私は (watashi wa) can be omitted, but just as a note, you cannot put a particle directly in front of です (desu). When we want to emphasize location, you're right again, we use に, but with います (imasu) for living things or あります (arimasu) for nonliving things.
(Watashi wa) soto ni imasu.
外（そと） is 'outside'. 大外刈（おおそとがり）is individually the kanji for "big" "outside" and "harvest" so "major outer reaping" isn't the worst way to express that in English (I'm assuming 'throw' is because it's a throwing type move?)
but, 外（そと） alone, is 'outside'. outer, as in 'the outer edge' of something, would be more like 外縁 (がいえん）(although I think even in this case 'outside edge' is probably still correct.)
I assume you're probably using google translate? Google translate is notorious for incorrect translations, especially if you are only writing in hiragana. There are many homophones in Japanese and rather than give you all of the words that use a certain reading it gives a random one, usually the wrong one for the context you want.
A proper dictionary like Jisho will help you immensely https://jisho.org/search/%E3%81%9D%E3%81%A8
Soto and Sotogawa both mean "outside" but they have different nuance/uses
The difference between 外・そと soto and 外側・そとがわ sotogawa here: http://japanandthings.blogspot.com/2010/10/difference-between-and.html
外側 is not a word in the JLPT so I'm not sure Duo even covers it
I'm not sure why it would give you "gently" since that would be そっと sotto, a different word with a different spelling/pronunciation
My best guess is because it was hiragana rather than the kanji for 外 "outside" it tried to shoehorn in the next closest thing that strictly uses hiragana when written
With an IME after typing in hiragana, hitting the space key will convert it to kanji or katakana, pressing again will let you cycle through different options. Hitting enter after will lock in that selection.
On a phone the kanji options will show up as you are typing in a list above the way an auto-fill suggestion would.
お by itself is just a regular o sound. おお or おう is the long o sound. They are pronounced differently, so the spelling of the word depends on the pronunciation. Tofugu has an article with sound files you can listen to comparing long and short sounds: https://www.tofugu.com/japanese/japanese-pronunciation/
外 is just the noun "outside"
外は寒い "It is cold outside" [Topic: outside] [Is cold]
外に has particle に which indicates the target of destination/action or location of existence; functioning similar to the prepositions "To, at, in (with nouns that take them, 'outside' usually doesn't in English)".
犬は外にいます "The dog is outside" [Topic: Dog] [location: outside] [Exists]
外に出ます "I will go outside" [destination: outside] [Exit] (leave the interior to the outside/exterior) or 外に行きます "I will go outside" [destination: outside] [Go] "Go to the outside/exterior"
Far less commonly, though it will appear in dictionaries, it can be used as an adverb meaning "in addition, besides" though that is usually written instead as 他に・ほかに
他に何かいりますか - "Do you need anything else?" [in addition] [something] [Is needed?]