I couldn't find specific mention of laser weapons in general making any noises. I'm sure there's a faint hum and there's a sound of a discharge.
Correct. There's actually be a noticeable crack, kind of like the sound of a static discharge, just louder.
If so, would the suppressors or silencers work as attachments? Sorry if this is in the book, I haven't read through it fully yet.
No, as both those devices suppress and silence things that are specific to how a gun operates. What you hear from a gun is expanding gasses of the propellant. Lasers don't make noise by expanding gasses. The crack is actually the small vacuum tube that is made along its path.
Also note that if a gun fires supersonic ammunition, you'll still hear the sonic boom of the projectile.
Paul