It's not a special case or idiomatic. Irish contrasts a bunch of stuff you'd just use the progressive for in English.
When you use 'ag [vn]', it implies it's something you're actively doing, thus 'tá mé ag snámh' = 'I am swimming'.
On the other hand, you use 'i [poss] [vn]' when referring to a passive activity or state. Thus 'tá tú i do chodladh' = 'You are sleeping'. If you wanted to say 'I am sitting', you'd say 'tá mé i mo shuí' - both are states or passive activities.
Using the latter form for swimming would imply that you're unconscious or being dragged along. Using the former for sleeping or sitting would imply that you're somehow actively sleeping or that you've grabbed the edges of the chair and are pushing yourself into the seat, or more realistically that you're in the process of going from standing to sitting.
There's a bit more with 'ag' that I guess would be worth covering. If you wanted to say that Síle is kissing Pól, you'd say 'Tá Síle ag pógadh Pól'. Simple enough. But if you had a pronoun as the object of 'pógadh', you'd use 'do [poss] [vn]' instead: 'Tá Síle do mo phógadh' - 'Síle is kissing me'.
There are also some fixed idioms that use 'ar [vn]', but I can't recall any off the top of my head.
From your explanation, this seems to me to be very similar to active vs passive voice in English. Of course, I could very well be wrong, but hopefully if other, more skilled, speakers of Irish come along, they may be able to prove me right (hopefully!)
It's not related to the active and passive voices, it's just that the terminology I used was similar.
'Active' and 'passive' when referring to voice refer to who the subject of the clause is. In an active voice clause, the actor [https://en.wikipedia.org/wiki/Agent_%28grammar%29] (the one performing the action) is the subject, whereas in a passive voice clause, it's the 'patient' [https://en.wikipedia.org/wiki/Patient_%28grammar%29] (the target of the action) who is the subject.
However, when it comes to these two verbal noun constructions, the 'ag' one refers to something which is actively ongoing, whereas the 'i' one refers to something which is simply a state of being. In the case of sitting, the 'ag' construction thus refers to you going from a standing position to a sitting position, while the 'i' construction refers to the end product of that change: the state of sitting. With sleep, while you ware the one doing the sleeping, it's not something you actively do, but rather it's a state you're in.
The Irish course has human audio instead of computer generated audio like the Italian course. Therefore, the Irish pronunciations take more time and effort to pronounce (but it's worth it because they are more accurate!). However, every word in the Irish course is pronounced at least once, so you are guaranteed to hear every word at least once. If you want more pronunciation help, visit forvo.com.
well so far we've been learning habitual present like Codlaim "I sleep". here we have the other form of present which is not explain in the Verb present 1. so am I the only one having a problem whit this ?
codladh what group is that ? has to be the second one but is it leathan or caol ?
Codlaim isn't the habitual present, it's the simple present. Only 'Bí' has an habitual present (bíonn).
'Codladh' is the verbal noun of 'codail' ('sleep'). You're correct that it's second conjugation. Specifically, it's second conjugation because it's a syncopated polysyllabic verb with a dictionary form ending in -il. However, 'codail' is a bit of a weird verb, as it acts as if it's actually 'codlaigh', which is a variant spelling of the verb. This means that rather than being conjugated like, say, 'imir', it actually conjugates more like a second conjugation verb ending in -igh, but for various etymological reasons, the verbal noun's ending is spelled irregularly though the pronunciation is regular: as -adh rather than the expected -ú. For instance, the word for 'opium' in Irish is 'codlaidín', which is the diminutive of 'codhladh'.
What you're learning in this exercise is the present progressive. I wrote up some notes that might help: https://i.canthack.it/the-progressive-in-irish.html
There were no explanation of the present progressive at this point. This sentence is a bit confusing and feels out of place when we try to get used to conjugating the present habitual, I hope this will be addressed in 2.0 (either move this sentence to the lesson that explains present progressive, or add notes to explain it summarily in Verbs I).
No. It's distinguishing between two kinds of continuous action: it distinguishes between action you're actively performing verses ones you're passively performing. As an example, positioning yourself so as you can sit in it would be something you're actively doing, whereas when you're actually sitting in the chair, you're fully seated and thus only passively performing the act of sitting.
Using the example here, 'tá tú ag codladh' would be like saying 'you are trying to fall asleep', whereas 'tá tú i do chodladh' means that 'you are now actually sleeping'. In the former, you're trying to enter a particular state, whereas in the latter, you've achieved that state, and it's ongoing.
I'm not sure what you mean. This has nothing to do with any of that. This is one of the forms of the present progressive.
'Tá' (the name of the verb is actually 'bí') is the existential verb (there is, there exists), whereas 'is' is the copula and expresses something more like equivalence.
Also, I think you might be confused about 'mo chapall' and 'capall agam'. The latter is just a meaningless sentence fragment unless you have the verb 'bí' in the sentence, e.g. 'beidh capall agam' = 'I will have a horse', 'bhí capall agam' = 'I had a horse', 'tá capall agam' = 'I have a horse'. 'Bí + ag' is how 'have' is expressed in Irish.
No, it's not that different; it just requires some changes to the verb part of the sentence. You just phase it as a question: An bhfuil tú i do chodladh.
In that sentence, 'An' is the interrogative particle (marking it as a yes/no question). 'Fuil' is the dependent form of 'tá', and is subject to eclipsis because it's preceded by the interrogative particle, thus it's written 'bhfuil'. The rest is as in a normal sentence.
So, where in a regular indicative sentence you have:
<independent verb form> <subject> [<object>]
In a yes/no question, you have:
'An' <eclipsed dependent verb form> <subject> [<object>]
Here are more details on how the various verbal particles work: http://nualeargais.ie/gnag/part.htm
When an activity is active in English, e.g. "I'm running", it corresponds one-to-one with the Irish, "Táim ag rith". However sometimes the English "-ing" is used to describe a state, e.g. "I am sleeping" = asleep, or "I am sitting" = seated.Then in Irish it's "Táim i mo chodladh" and "Táim i mo shuí".