Green - they have just staggered the numbers on the tab as the font is too big otherwise. You can see on the regular stave the chord is all played together.
Orange/Red - this is normally just a strum.
Blue - no idea. They might mean ‘let it ring’ but I’ve not seen that before.
My guess is that it is just emphasising that this is a chord and all the notes should be played as a single strum. Why is the same notation not on the notes highlighted in green, no idea.
I can neither confirm or refute what @mathsjunky said. For the orange slash I would expect the notes to be repeated if you are intended to play them again, with or without the beam connecting the notes as you see in the final two notes of that bar. Maybe just trying to simplify given the number of notes being played as a chord.