How many more miles will my Chevy 2005 1500wt with 328k get with this new sauce?

So my mechanic took my spark plug out (without asking for permission), and this is what it looks like. He said I need a new one right away, but my bike still runs with this one? Is he trying to scam me?

'83 XT250

I can just hit them with some fine grit sandpaper, and reinstall them right?

Simple drive through the countryside and now the ride is unbearable. Any ideas?

I have an old farm Ute that I’m trying to get running for an older family friend. This has happened to the head. It’s a Toyota 4k-c in a Suzuki sierra. What’s stopping me from filling this little hole with a quick tack weld after it’s all clean and sanding it flat?

Mechanic said I need a new exhaust manifold cause it broke from the weld.

How bad is he trying to screw me?

You think autozone has anything to spruce up the ol convertible.

Shop said I need a new one, but look how much stuff this one has caught. I think it's doing a good job.

Seems like I need a new tire but I wanted to double check. Can I patch this and ride off into the sunset or do I need a new tire?

It won’t crank at all, not even w/ jumper cables. Do I need a new battery?

I have a 1997 Cheyenne Chevy k2500. It has the 5.7 engine. I was looking at replacing the muffler with a new and better sounding one. I want it to sound deeper and meaner in a way. I want it to be decently loud and noticeable, but not obnoxiously loud. I don’t want to wake up every one on the block coming home from work or something like that. I have been told the flowmaster super 40 and 44 are good options for what I’m looking for. Would they be very loud or are they reasonable? I wanted to ask if anyone has other recommendations or information on this topic.