Hello, welcome to the forum - I'm pretty new myself.
Others here are vastly more knowledgeable than me, but I will try to answer your questions. I'm assuming you are referring to the Liturgy of the Hours? The music for this has not been published in any one place, as far as I am aware. Solesmes have published all that is necessary for Lauds and Vespers of feasts (in Latin), see their website for the Antiphonale Romanum I and II. There is also the Ordo Cantus Officii which lists all the antiphons needed for the Liturgy of the Hours - however, it only tells you where to find them, it doesn't give you the chant. I believe there is a project somewhere that has put all the antiphons into this as some online thing, but I've not seen it, and because of the layout of the Ordo it is not useful for chanting the Office every day.

For the Office of Readings, as it is now called, I'm not aware of a resource that provides the chant for that but ready to be corrected.

For singing the Liturgy of the Hours in English, I don't know if there is anything that is comprehensive, or official - also happy to be corrected on that! You can find psalm tones such as the Meinrad tones for chanting the psalms, and some antiphons etc may have been set to neo-Gregorian chant in English, I'm not sure.

Have you considered chanting the 1962 Breviary? Others on here would suggest earlier breviaries too. The 1962 is the one 'officially' permitted by Pope Benedict (and sort of ignored by Traditionis Custodes), but I have read good arguments for the legitimacy of praying the older Breviaries. There are considerably more resources for the 1962 than the new Liturgy of the Hours - it is this version of the Divine Office that I am learning to chant.

Stimson is quite right about the abbreviations with the antiphons, they refer to the traditional Psalm-tones which (as far as I am aware) are really only suitable for Latin.

I think the Liber Hymnarius that you refer to is for the Monastic Office, which is a bit different. I wasn't aware that it contained antiphons, I thought they were in the Antiphonale Monasticum, but I could be wrong.

I know nothing more about the Liturgy of the Hours - others here do - but if you're interested in the 1962, PM me, and I will try my best to answer your questions! Also worth researching the differences, like the fact that the Liturgy of the Hours suppressed certain psalms, so you wouldn't be praying a complete Psalter, among other differences.

To 3 and 5: the lowercase letters in the old office are any note not the final of the mode. Capitals are the final. They are all lower case in postconciliar editions of the reformed liturgy. There are some trying to make postconciliar editions of the old liturgy where this won’t be observed. I think that this is one older convention to maintain.

1. Somewhere in the ordinary or the Toni Communes.

2. The older antiphonal is the Liber antiphonarius (if you use Solesmes), otherwise the Antiphonale Romanum. The most frequently used material is in the Liber Usualis. Two volumes are available for the Liturgia Horarum for Vespers and Lauds respectively, Antiphonale Romanum vol. II (Vespers) and I (Lauds).

There are also the pre- and postconciliar editions of the Antiphonale Monasticum if that floats your boat, and for English, there are a couple of attempts out there.

6. For offices according to 1962 (we hope one day to do more with it; I prefer the pre-Pius XII office which has some noticeable differences): Ecce.

Hi @samatizer03,

Welcome to the forum!

Here are some things that would help.

Try this tool for your question #6: Brevarium Gregorianum.

And here are some tutorials I gave back during covid on chanting the monastic office. It's not the same office as used in the resource above, but you'll find answers to your questions 3 and 5. See especially the Vespers part 2 video.

Chanting the Monastic Office (Vespers and Compline) Instructional Webinar

Welcome, @samatizer03

People keep directing you to resources for the traditional office; I'm not sure why. To answer your questions:

1. see pp. 62-90 of the attached pdf (excerpt of the 2009 vesperale, which also has psalm antiphons for Sunday vespers of the 4-week psalter)

2. Our friend Joerg Hudelmeier has transcribed the antiphons for all hours of the reformed office here (web version with links to gregobase here ). It does not contain the psalms, readings, etc, which you can find in ibreviary or Universalis (the app I use). Universalis is a little more flexible and lets you read in parallel Latin/English.

3. The psalm tone matches the tone of the antiphon attached to it

4 & 5. Answered by others above

6. There's no site yet that does for the reformed office what Brevarium Gregorianum does for the '62, but with the resources that do exist you can put together what you need for any hour.

The 2 volumes for Lauds and Vespers of Sundays and feasts in the reformed office can be purchased through Paraclete Press if you're in the US, or through Solesmes directly if you're in Europe. These will have everything you need for those hours. NB: they are expensive.

I know it is pre-V2, but the work reflected is considerable at https://breviariumgregorianum.com.

I always recommend the Traditional breviary,

ditto

isn't that a self-contradictory title? A breviary, by definition, has text and no music.

It's what musicologists/codicologists call breviarium notatum.

Breviary is a book putting together all the texts (which in choir would originally be read from several different books by different roles/persons). There's nothing contradictory about adding also music to the compilation.

I stand corrected!