On the old forum Neqitan had created a post (I can't think of the word) called "La Esquina Español" so Spanish learners could ask help from him and others in their Spanish learning. I hope no one minds that I recreated it.

My first question is what is the difference between "ir a infinitivo" and "infinitivo + -é -as etc." for the future tense. My first idea was that ir a infintivo was used for certainty and the other was not.

It should be either "La Esquina Española" or "La Esquina DEL Español" for that matter! (But since Simon has forbidden editing one's posts this is gonna stay for long. Dammit.) The original title was "La Esquina: Spanish corner".

About your question, some say ir a + infinitive recalls a nearer future than the future conjugation, others say that ir a + infinitive is more used in the spoken language than its counterpart, but me, both are terribly similar.

And by the way, the future conjugation is not that sweet. There are many irregular verbs so taking the infinitive plus the suffixes (é, ás, á, emos, áis, án) won't always work:

venir (to come) -> vendré, vendrás, vendrá, vendremos, vendráis, vendrán
decir (to say, to tell) -> diré, dirás, dirá...

We could say that these verbs inherited a distinct stem:
decir -> dir-
venir -> vendr-
caber -> cabr-
poner -> pondr-
poder -> podr-
saber -> sabr-
salir -> saldr-
tener -> tendr-
valer -> valdr-
querer -> querr-
hacer -> har-

...and there are some more apart from those.

I'm really sorry, but I fixed it.

Oh yeah I forgot about those I should have said regulars considering I knew about those changes...

I have another question.

The Spanish subjunctive seems to me pretty easy. You simply change -ar endings to -e and -er/-ir endings to -a. You use it after constructions like Espero que, deseo que, dudar que, etc. that express (I'm explaining this badly, sorry) non-indicative qualities such as: desire, doubt, and necessity. Accounting for irregulars and stem-changes I don't see what is especially challenging about the subjunctive. Am I missing something?

Yes, you're missing many usages. You've just learned how to use it in relative clauses starting with que, that's just the tip of the iceberg, trust me.

Not to mention the fact that, even with these, there are complications. For instance, both of these sentences are equally correct:

(1) Espero que ella tiene dinero.
(2) Espero que ella tenga dinero.

There is a subtle distinction in that the first expresses more certainty than the latter. You might capture this in English translation with "I expect she has money" vs. "I hope she has money", but that's only a rough approximation and wouldn't work for other matrix verbs.

Yep, that's correct Linguoboy. The former is making a slight assumption that he/she already has money, while the second one slightly hints a future tense (you more or less hope he/she'll have money at a future point).

Hay tantas esquinas no creo que tenemos un cuadrado ahora. Jaja. ¿Qué forma creen que tenemos ahora? Lo siento para el puesto de azar.

Correcte por favor.

¡El tridecágono!
The triskaidecagon!

I have no idea how to translate "random post", that's more like English-speaking Internet culture. But at least I'm sure "post de azar" is wrong. :S

Espero que Juan va a la escuela.

Yo sé que Juan va a la escuela.

Es cierto que Juan va a la escuela.

Espero que Juan vaya a la escuela.

Quiero que Juan vaya a la escuela.

Dudo que Juan vaya a la escuela.

Es bueno que Juan vaya a la escuela.

No pagaré hasta que Juan vaya a la escuela.

I understand what linguobuy meant now. My dictionary states that esperar means to expect, to wait, to hope (mainly in subjunctive).