1. Will callouses develop on the length of my index finger so that I can grip bar chords easier?
2. What does "x" mean on a guitar tab?
3. Also I'm trying to play this song but it has two notes on non-adjacent strings. It's not a finger picking song... Confused me is confused.

Please answer thoroughly and thanks <3
No, well they shouldnt unless you play nothing but bar chords all the time.
X means mute the string, usually with your left hand as palm muted notes generally have a pm above them
You pick all three strings at once and your first finger should slighty touch the string you are not fretting to mute it
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3. I assue it's something like this


To mute the string inbetween hold down the lower string with the index and rest your index finger up against the middle (muted) string so that it makes contact but your not pressing down on the string.
For barred chords you just need to develope the finger muscles, i been going for 20 years, and some of my fingers are rough, but no calluses really other than the tips. answer to 3 is well....you have to mute the strings you arent playing, but this can be worked around if you learn how to hybrid pick and uses the fingers not holding the pick to pick strings that are skipping a string.

its how i do those things no adays, but thats because i like the sound of them that way.
Callouses really aren't a big deal. I've played guitar for three years and I had four years of violin before that, but I still don't have callouses on either hand. Strangely enough, I don't have any trouble playing because of it.

The 'x' is a dead note. You simply mute it by laying a finger (usually it's your index finger, but others are used occasionally) on that string to prevent it from ringing out.

When playing non-adjacent strings, you simply skip over that string. If it's not fingerpicked, that just means that you ignore the string(s) in between and skip over them. String skipping is an important skill to develop, since it's pretty common to skip over strings and not play them solely in ascending or descending order.
The callous thing is a big myth - i've been playing over 20 years and haven't had callouses on my fingers for yonks. For the first few months yes, your fingertips will dry out a lot and look a right mess but a lot of that is because you're not used to playing and are pressing too hard. Eventually your hands get used to it and althogh the skin might be a little tougher you won't have rock-hard skin over the tips.
Actually called Mark!

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