Both translations, Douay and KJ, correctly translate "χαιρετε" as "all hail". Compare "χαιρε" in Luke 1:28. "Hello" would not match the elevated style of the Gospel but in a context of another book would be correct. In fact, in modern Greek, "χαιρετε" is a frequent greeting of several people, -- you'd hear the word often.
I use mostly unbound.biola.edu. Include "Greek NT: Byzantine/Majority Text (2000)", or any other Greek variants among the versions, pick the chapter and verse segment, and it will let you copy and paste from Greek or Hebrew, or any other language.
www.blueletterbible.org is less convenient for quick searches but works as well. Here's John 1:1 from Textus Receptus:
Ἐν ἀρχῇ ἦν ὁ λόγος καὶ ὁ λόγος ἦν πρὸς τὸν θεόν καὶ θεὸς ἦν ὁ λόγος
A difficult decision is whether to choose accented or unaccented Greek. I prefer unaccented, but opinions probably vary.
If you want a Greek keyboard, you probably will have to either buy one with the keys marked in Greek, or make one using phonetic match, so you don't have to remember what English key is what. For Windows there is Microsoft Keyboard Layout Creator. Also there may exist online virtual keyboards for Greek.