Are those assumptions about "よう" correct?

I had some doubts about the "よう" expression in japanese and searched through forums, apps, dictionaries and finally made some assumptions myself. The problem is that I'm a self taught student and I don't know anyone who speaks japanese, so could you guys see if those assumptions are correct and if they're not, correct them? Thanks!

#1 - You can use "ように" to say that "[x] is as [adjective] as [y]" / "[x] is equally [adjective] as [y]". e.g.:

- "お父さんがお母さんのように大きい。(My dad is as big as my mother.)"

#2 - You can use "ように" to say that "[x] is like [y]" ([x] isn't [y], but it looks like it). e.g.:

- "君がお父さんのようにです。(You are like my dad.)"

#3 - You can also use that same format with any other verb to say "[x] [verb] like [y]". e.g.:

- "君がお父さんのように歌う。(You sing like my dad.)"
- "君がお父さんのように話す。(You talk like my dad.)"

#4 - You can use "よう" to say that "[x] seems like/looks like it is [y]" (I don't know if it is [y]). e.g.:

- "君がお父さんのようだ。(It seems like you are my dad.)"
- "彼が学生のようです。(It seems like he is a student.)"

#5 - You can also use "よう" to say "it seems like..." e.g.:

- "私に手紙を書いたようです。(It seems like you wrote a letter for me.)"

#6 - You can use "と見える" and "ように見える" to mean same thing as above. e.g.:

- "私に手紙を書いたように見える。(It seems like you wrote a letter for me.)"
- "私に手紙を書いたと見える。(It seems like you wrote a letter for me.)"

#7 - You can use "ようにする" to describe an effort to do something. e.g.:

- "来年はフランス語を勉強にする。(Next year I'll try to study french.)"

#8 - You can use the adverbial form of an adjective + "と見える" to say that "[x] looks like it is [adjective]". e.g.:

- "この食べ物がおいしくと見える！ (This food looks like it is delicious!)"

So, could you tell me if those are right or wrong? Thanks!

I don't know if I would break it down into this many patterns when I try to teach students, but anyways :)
A few comments:

- The example sentence in 2 is incorrect.
君がお父さんのようです。you don't need the に.

- The example sentence in 7 is incorrect.
来年は、フランス語を勉強するようにする。

- The example sentence in 8 is incorrect:
この食べ物はおいしく見える。 (This food looks good.)
この食べ物はおいしそうに見える。would be another way to say it.
この食べ物はおいしそうだ。would be the natural way to say it.

Are those assumptions about "よう" correct?

I think you do understanda よう correctly. But it's the other expressions that are wrong. Please refer to the following changes I've made to make the Japanese sentences fit their translations.

お父さんがお母さんのように大きい: My dad is big just like my mother. (My mother is a big person too.)

君はお父さんのようです。: You are the one who are like your dad.

君は父のように歌う。: You sing like my dad.
君はお父さんのように話す。: You talk like your dad.

君がどうやら父のようだ。: It seems like you are my dad. (I don't know what my dad looks like.)
彼が学生のようです。: It seems like he is the student.

私に手紙を書いたようですね。: It seems like you wrote a letter for me.
私に手紙を書いたように見える。: It looks as though you wrote a letter for me.
私に手紙を書いたと見える。: It seems like he wrote a letter for me.

来年はフランス語を勉強するようにする。: Next year I'll try to study french.

この食べ物がおいしく見える！: This food looks as though it is delicious! (although it is not delicious)