The most complete collection of texts on Arianism I know of is listed on the FCC website, but they are Mostly letters from and to Arian Auxentius. Most of the texts have links in the translation column.
The online book "Arianism: Historical and Theological Reassessments: Papers from The Ninth Century" contains source texts and commentary on the liturgy AFAICS from the search function:
The letter of Arian Auxentius regarding the Arian missionary Ulfilas, gives the clearest picture of Arian beliefs. The creed of Arian Ulfilas (c. 311 – 383), which concludes a letter praising him written by Auxentius, distinguishes God the Father ("unbegotten"), who is the only true God from Son of God ("only-begotten"), who is Lord/Master; and the Holy Spirit (the illuminating and sanctifying power), who is neither God nor Lord/Master:
I, Ulfila, bishop and confessor, have always so believed, and in this, the one true faith, I make the journey to my Lord; I believe in only one God the Father, the unbegotten and invisible, and in his only-begotten son, our Lord/Master and God, the designer and maker of all creation, having none other like him. Therefore there is one God of all, who is also God of our God; and in one Holy Spirit, the illuminating and sanctifying power, as Christ said after his resurrection to his apostles: "And behold, I send the promise of my Father upon you; but tarry ye in the city of Jerusalem, until ye be clothed with power from on high" (Luke 24:49) and again "But ye shall receive power, when the Holy Ghost is come upon you" (Acts 1:8); Neither God nor Lord/Master, but the faithful minister of Christ; not equal, but subject and obedient in all things to the Son. And I believe the Son to be subject and obedient in all things to God the Father
A letter from Arius (c. 250–336) to the Arian Eusebius of Nicomedia (died 341) details the core beliefs of the Arians:
Some of them say that the Son is an eructation, others that he is a production, others that he is also unbegotten. These are impieties to which we cannot listen, even though the heretics threaten us with a thousand deaths. But we say and believe and have taught, and do teach, that the Son is not unbegotten, nor in any way part of the unbegotten; and that he does not derive his subsistence from any matter; but that by his own will and counsel he has subsisted before time and before ages as perfect as God, only begotten and unchangeable, and that before he was begotten, or created, or purposed, or established, he was not. For he was not unbegotten. We are persecuted, because we say that the Son has a beginning, but that God is without beginning.