と - used for both "if" and "and"?
 

How do you tell the difference between the two?

On tae kim's page:

学校に行かないと友達と会えないよ
If you don't go to school, you can't meet your friends.

is it not possible for this to also mean-

you don't go to school and you don't meet your friend

It is not possible because the "and" use of と is only for connecting an exhaustive list of nouns.

That is NOT possible. と can only mean "and" when it is connecting nouns, not anything else.

日本とアメリカ
ボブとメアリー

EDIT: Yuriyuri beat me to it.

so you can only use it to say something like お金と薬, right?

How would you express the "and" in this sentence then?

You didn't go to school and you didn't meet your friend

Most naturally, 「君は学校に行かなかったので友達に会えなかった。」 .

You can also say 「君は学校に行かなかった。だから友達に会えなかった 。」.

I'm not sure if this is the best illustration of what OP was asking about, but I don't think it's necessarily your fault that you translated these the way you did. I suspect OP was just trying to think of two random, unrelated actions to connect with "and" so he could see how "and" between two verbs is formed in Japanese.

Unfortunately, the two actions he picked could be pretty related (i.e., one caused the other), so you correctly used a ので construction.

OP, if you just intended to have two completely unrelated actions (i.e., "ate sushi" and "played the piano"), say, to list what you did during the day, a couple options to connect them as one sentence come to mind right now: 〜たり〜する and 〜て.

The former is an incomplete enumeration of activities: "Today, I ate sushi and played the piano [and did other stuff]." The latter is just a list (that could be in chronological order): "Today, I ate sushi and played the piano."

The sentences are:
今日はすしを食べたりピアノを弾いたりしました。
今日はすしを食べて、ピアノを弾きました。

You also could do a variation on the latter. There is an alternative to the 〜て form that is basically a more "professional" (I am trying not to say "formal" so much when describing some Japanese stuff). The form is basically to make the 〜ます form but don't say ます. I don't know what else to call it. Conjunctive form? I think we English speakers at my Japanese university would refer to it as "pre-masu form."

今日は食事し、ピアノを演奏しました。

Note: 食事する is a more high level word that means 食べる (to eat), although I think you only 食事する an entire meal rather than just a certain food. 演奏する is a more high level word that means 弾く (and the other verbs that mean "to play [a musical instrument]").

Note to advanced speakers: I realize the above "high level" sentence sounds really weird because it's unlikely you'd say such a simple thing of what you did today in such a high level way. I just wanted to show the other way I could think of to link separate actions as one sentence as the equivalent of "to do ~ and to do ~."

To OP: To form the 〜たり form, you form the plain past of the verb and add り to it.

I think saying the word AND can be misleading. What you get is a time adverbial clause. Instead of using the word AND I would use more the word WHEN.
When foreigner study English are introduced to what is called IF clauses (if I...then...). The thing they teach us is that the same relation of the tenses in a IF clause is present also when you find WHEN...this creates some confusion when you face the conditional in Japanese.
I will write to you what one of my books says about と...I think it explains it pretty well.

と follows a verb or an adjective in the plain present form and creates a time adverbial clause or a conditional clause depending of the tense of the main verb.
If the main verb is in the past tense, the clause with と functions as time adverbial clause, and the entire sentence expresses what happened after some event.
図書館に行くと、高橋さんがいました

This is where you get the AND, because in English it works well with both WHEN and AND. So you can say both "when I went to the library Mr Takahashi was there" and "I went to the library and Mr.Takahashi was there".
Similar situations can be created when the verb in the main phrase is not past, but I cannot write out the whole book.

Instead of trying to find a translation, try to understand the meaning of と. When I see it I immediately think that its purpose is to show 2 consequent actions in which the speaker has no control over. When you find it with a present tense in the main phrase you fall in a natural consequence.

I've always called it a "Stem" (語幹?)
I say that because I think the Japanese word was something like 動詞語幹 but I can't really remember if that was correct or not.

Alright I think I got it from the posts above. To summarize:

たり or て combining two unrelated events
ので combing two related events
と combing two nouns / when x then y [x] と [y]

Close enough to start. Now try to compose some sample sentences using each of these and we can help refine your understanding.

Go easy on me..!

たり:

テレビゲームを遊んだりご飯を食べた (I played video games and I ate a meal)

ので:

彼は野球が大好きですので投手です (He likes baseball and he's a pitcher)

と:

外に行くと寒いです (When I go outside, I will be cold)

I try to give you my input...better ones will follow :)
たり：
遊ぶ=play as in having fun, not play a specific game.
The last verb of the list closes the phrase with たり+する

ので:
ので means "because", so your phrase would means: he is a pitcher because he likes baseball...or since he likes baseball he is a pitcher.

と：
I'd say you will have to see the context for this one. It has to be a natural consequence that you cannot control. So I think if we live in the north pole that would be a plausible phrase :)
I think in English would make sense too only due to the context.
EDIT: I forgot the main part...I was talking about your English phrase. Because the Japanese one is not correct due to a wrong choice of word. 寒い is referred to a habitat temperature. To say you are cold...I guess I could say 寒気がする, but always wait for better suggestions.