"You misread buff :3 I know Nuwas are already strong but it's only a slight buff, like $1900 to $2000, %5, really, and aren't all that great if your opponent knows what he's doing (Charon Tanks / Mortar Quads, SCUDs, Zephers, EMP, Psychics, so on)"
This unit deserves nerfs, not buffs. Making it more powerful will only encourage massing them, even if price is increased. Stubborn you are, sir.
"I suppose, but it wouldn't be too bad because you could just micro your units away from the fire, and it'd take more to have them kill instantly due to their nerf. It's a traid off system, not really a buff."
micro units away from fire = time spent not firing on enemy = enemy keeps firing = your units die even faster
About miner issue, i thought you did play "Happy Birthday" map. If you didnt, do it, build refinery, read what shows up and learn to manualy manage your miners.
"- Make drillers able to drill into vehicles / infantry /structures to do damage?"
No, just no. They are supposed to be specialized transport, not specialized kill you from underground unit.
"- Make it so Sedge Cadres (or all prism stuff) "blind" (reduces attack damage toward) infantry (Only infantry)."
Already reserved for Riot Troopers (check Developer Playthrough A05 Bad Apple)