good of you to...
Your actions in a particular situation were appropriate, and maybe exceeded what could reasonably be expected of you.
It was good of you to take Geoff home last night: he was so drunk that I was worried about him!
good for you to...
Your actions are/will be beneficial to you.
It's good for you to get some healthy exercise every day
It is often used in a conditional form:
It would be good for you to get some healthy exercise every day
good to you to...
As this NGRAM shows, this expression is uncommon and, when used in this context, seems to mean the same as the for version.
It occurs more often in sentences like this:
Does it sound good to you to go to the beach tomorow?
“How are you doing?” and “How do you do?” are questions asking about how someone is feeling, although “How do you do?” has a more formal register to it, and I wouldn’t expect to hear it very much in the US, except perhaps in a formal introduction.
As often as not, these two questions are used as a form of greeting, and the person asking the question isn’t necessarily looking for an answer to the question. However, that’s partly contextual. If I’m recovering from surgery, and a nurse asks, “How are you doing?” I’ll assume the nurse wants to know if I’m in pain or not. If I’m walking down the hallway and a coworker asks, “How ya doin’?” as he’s passing by, I’ll assume it’s just a friendly greeting, and answer with something like, “Good, and you?”
On the other hand, “What do you do?” is a question that’s usually meant to ask what you do for a living. In other words, the person could ask, “What kind of work are you in?”
I wouldn’t expect to hear both questions asked without an answer exchanged in between them. So, a dialogue might go something like this:
"Hello, how do you do?"
"I’m doing fine, thank you. And you?"
"Quite well. May I ask, what do you do?"
"I’m a carpenter."
"Well, it sure must be nice that the weather is getting warmer.”
That dialogue shows what your questions mean, but it’s more formal than most friendly introductions might be. In a more informal setting, that conversation would sound more like this:
“Hey, how’s it going?"
“Pretty good – you?"
“I’m fine, thanks. You know, I just realized, I don’t know what line of work you’re in."
“Oh, I’m a carpenter."
"Well, you must appreciate this nicer weather we’ve been having.”
Best Answer
First of all, you can't can "I have find." You are trying to use the Present Perfect tense, aren't you? So, "I have found a good friend in you" is grammatical, unlike "I have find... ."
Now the question is what's the difference between the present simple (I have) and the present perfect (I have found). Well, if you say "I have a friend," you are talking about possession: I have a mother, I have a job, I have a car, I have a friend.
If you say "I have found a friend," you are talking about an action which is completed by now: I have bought a car (so, I have a car), I have watched the film (so, I know what it is about), I have found a good friend in you (so, I have a good friend in you).
All in all, sentence 2 is about the action which has led to the result, and sentence 1 is about the result.
Having read the comment below my answer, I'd like to add that if you say "I find a good friend in you," you mean a regular activity. It's like "I always/usually/regularly find a good friend in you."