I bought the book because I had been told that it was an interestig book and I liked it more than I expected.

Faltas solamente una coma después de la palabra <em>book</em>. The clause after <em>book</em> states its own subject, so even though the subject of the last part is the same as that of the first part (namely, <em>I</em>), the comma is necessary. Así: "an interesting book, and I liked it . . . ."

Options for the ending would be as follows:

". . . I liked it more than I expected." (your original choice, totally acceptable)

". . . I liked it more than I expected to." This sounds a tiny bit more complete to my ear (here, <em>to</em> takes the place of "to like it," from the more complete but also much longer ". . . I liked it more than I expected to like it," which is correct but unnecessarily cumbersome).

". . . I liked it more than I thought I would."

". . . I liked it more than I thought that I would." 

Ignatius is very lazy and is worried about modern life. Here, there is no new clause for the verb following <em>and</em>, so you have correctly avoided any comma usage.

He has odd political ideas, like his suppor to divine right and he managed not to work.

I'm not absolutely certain about this, but I think you want to say that he believes in divine right and that he figures out a way to avoid working. If that's correct, it would be ". . . support for divine right, and he manages not to work." The comma is used because the final clause (beginning with the second <em>he</em>) states its own subject. Also, you've begun with the present tense ("He <em>has</em> . . ."), so that would be maintained for <em>manages</em>, también.

. . . drunk mother forces him to get a job.

He is fired and after that he gets a job as hot dog buyer.

www.studyspanish.com/   ?

A fascinating notebook entry! Thanks for sharing this tidbit.

> A theory about how Spanish children to learn.

This is a very general statement about all Spanish children throughout all of time, so you'd use the present continuous <em>learn</em> here. It's also a title, so there would be no period at the end. Also, the first and last word and all internal words (except articles and prepositions of fewer than five letters) would be capitalized: A Theory About How Spanish Children Learn

You could also make the statement more general by saying <em>Spanish-speaking children</em>, since speakers of Latin American Spanish children doubtless experience the same phenomenon.

> When Spanish children have between three and five years old more or less,

<em>More or less</em> is a nice phrase to use here. Do set it off with a comma before as well as after, though. Also, the be-verb is used in English for age: <em>When Spanish children are between three and five years old, more or less, they</em> . . .

> so they couldn't learned it by listening.

When using the past participle (<em>learned</em>) like this, you'd need the auxiliary (helping verb) <em>has</em> in the appropriate person (como <em>he</em>, <em>hemos</em>, <em>ha, han, has</em>, habéis): <em>so they couldn't have learned it by listening</em>.

> I'm learning english, i wanna do it more interesting with language mates.

In English, names of languages are one type of proper noun (and, accordingly, they are capitalized). You would want the word <em>and</em> after the comma, since there is a grammatically complete clause on either side (on both sides) of the comma. Finally, the verb you want for the expression in the second clause is <em>make</em>: <em>I'm learning English, and I want to make it more interesting with language mates</em>.

As far as the word <em>mates</em> goes, it's common in Australian and British English, less so in American. <em>Mates</em> tends to mean something more like <em>pals</em> or <em>friends</em>, but <em>partners</em> is the word we'd be more like to use here: I'd go for <em>[name of language] </em><em>conversation partners</em>: English conversation partners, Spanish conversation partners, etc. More generally, I might say <em>language practice partners</em>.

Hope that is helpful!