Errors I've noticed.
I'm learning Japanese, having a good grasp of the language to start with I wanted to improve myself with this. But I noticed a few errors..... Some of which I find are basic. The errors happen in Hiragana 2, and they are the following:
One of the words is わたし which does me "I, me" (and "myself, mine, my" are related to this rather formal word). However the other meaning of わたし is "ferry" as in crossing something, it has neither "pass" nor "did" as a possible meaning.
Then we have こんにちわ which does mean "hello" but really means "good day", the にち in こんにちわ means "day". One of the translations, as provided by the drop-down translate menu, for こんにちわ says that it means 'good afternoon'!
Finally we have さようなら which is more along the lines of "Farewell" as in a permanent departing, even if it does mean "goodbye". You are far more likely to hear, or say, じゃまた when parting from someone for the day.
Another thing, one I hope will be addressed later, is that context matters greatly with Japanese. There are a lot of puns that can come up from a simple phrase.
Not sure where you're going with わたし. Depending on context it shouldn't be confused with 渡し (to send over; carry across; hand in). 'Crossing something' would be the intransitive 渡る（わたる）.
The last kana in konnichiwa is は, not わ. Also, afternoon is part of the day. In the morning you say おはようございます and in the evening it is こんばんは. I have no idea why 'good afternoon' is unacceptable to you.
I would agree with さようなら being used more for a long period of absence. But, then again, in English we don't seem to say 'goodbye' except under the same conditions as well. A simple 'bye' has a completely different nuance.