Good questions!
Sheet music, guitar chords and guitar tabs all can be read on the go. Guitar tabs are very visual - they show you where to place your fingers. Reading chords is pretty easy once you have memorized some of them and you have full flexibility how to play them. Reading sheet music is much more difficult because you have to learn how to link the written note to the right string and the right fret.

I learned to read sheet music when I was very young while learning to play piano. As a result, when I see sheet music I imagine a piano keyboard and each note has its own place. On the guitar, however, you can play the same note on a couple of strings on different frets. I find it very difficult to read sheet music while playing the guitar. If I spent more time on it I would get better, but I am pretty lazy

And it largely depends on the type of music you want to play. If you want to play classical guitar music there is no way around learning how to read sheet music. If you want to learn it for fun to sing songs, then tabs and chords are enough.

I learned to play the guitar on my own, but it took me quite some time. The very first challenge that you will have is to tune it right. There are online tuners available, so it shouldn't be a big issue.

Getting a lesson or having somebody to show you basics may be a good idea. I once taught a friend of mine to play some songs. Although she never played any instrument before, it went pretty fast.