I am new to utau, and would like help with learning.

Kasane Teto is not VCCV, and is not a beginner-friendly English voicebank. If you want to focus on English-language vocals specifically, you're better off using one recorded by a native English speaker as your first bank. Here's a directory of VCCV voicebanks: https://utaforum.net/threads/utau-vccv-voicebank-directory.10661/
In the process of using VCCV voicebanks, you may want to consult the official series of tutorial videos. This is the video specifically about making USTs, though you will probably want to consult earlier videos on the phoneme system as well.

This plugin may save you some effort in editing USTs by handling the conversion from words to phonemes. You will then only need to make the final adjustments, as well as other expressive tuning steps like pitchbends and vibrato. https://snowphones.weebly.com/lyric-parser-20.html

To answer your questions:
1) Teto is not VCCV. Teto uses a CVVC reclist by a person who goes by Delta that’s usually called Delta CVVC, and honestly English in general is not very easy to use in UTAU, but if you’re one to throw yourself into the deep end right off the bat, by all means. If you’re looking specifically for VCCV voicebanks, the links Kiyoteru provided above will be useful.

2) This question is moot. Romaji (no n, by the way) is for Japanese and we’re talking about English. English VBs usually use some kind of phonetic alphabet to represent pronunciation since English isn’t always spelled how it’s pronounced, so you’ll have to learn the phonetic alphabet of whichever method the voicebank you’re using, because different methods use different phonetic alphabets.

3) Kiyoteru provided a link above. It’s also generally a lot easier to make a MIDI in a different program like a DAW and then import it into UTAU than it is to make a UST from scratch in UTAU