Yes, the verse concerning Arca Vigraha is like this: "arcasiladhir gurusu naramati vaisnave jati budhi." The meaning is that one should not think of the Deity as made of stone, wood, etc. Another verse is, "Archaiam Evam Paria Ja Pujan Sadraya Hatay." The meaning is that one who worships the Deity with great devotion but doesn't show any devotion to the devotees of the Lord, or doesn't preach Krishna Consciousness for the benefit of the general public, he is in the lower stage of devotional service.
Yes, Sanskrit is spoken not only on Krishna Loka but also in higher planets, of the demigods. It is called the language of God and the demigods. It was spoken also on this planet, when people were all godly, they used to speak in Sanskrit. Sanskrit is the origin of all languages of the civilized peoples. It is most perfect, not only descriptive; the word "Sanskrit" means "the most perfect". Because not a single word you can pronounce without having a bona fide principle. It is not like the English language, "but, put" with irrational difference in pronunciation, no principles. Sanskrit isn't like that. Therefore it is perfect. It isn't whimsical. English poetry has one line one inch long, next line 600 inches long. Sanskrit is not like that. There are strict principles, and it is so beautiful. Therefore in Sanskrit language not an ordinary man can become a poet. No other language of the world can be compared with it. No other language of the world is so perfect as Sanskrit. Any language near to Sanskrit language (like Bengali) is nearer to perfection. Sanskrit is pronounced same way here or there, it is standard.