Concrete retaining wall repair

Hey, I've got an ancient load bearing wall that is doing it's job but is hideous with massive cracks and crumbling. It is so old and probably should be excavated and rebuilt but I cannot pay for that at this time and am interested in throwing some elbow grease and patchwork at it. I was thinking that i would rent a pressure washer because it was painted at one pount but its covered in moss algae dirt now however some spots are so bad it just looks like a bunch of rocks stuck together like a rice krispies treat. Wondering if there is some type of bonding thing i coukd paint on over what is there before proceeding or how to handle the prep here. Also, i'm on the fence about the process here. Was thinking throw some rapid set at the big holes and cracks then tack on some wire mesh or whatever you would use for some job like this, then scratch coat, then finish coat? Need some advice, not sure hiw pressure washing around small painted rocks will work.

I guess i forgot to mention this is an exterior wall not connected to the house. It's about 5' tall and holds up earth at the end of the driveway. That sika link you posted is intriguing. I wouldn't even know where to begin with that stuff.