Hi Dan,
1. If it smells like coolant when you pop the hood it could mean you have a sneaky leak somewhere... Check all pipes, cap, rad etc. I don't know what the set up is like on the V8's but on my m30 the hoses go right under the manifold so you wouldn't necessarily 'see' a leak, you'd have to feel for it (when its cool obviously!)
2. Your injectors may be loud this isn't a problem... Get a long screwdriver on top of the fuel rail and put it to your ear and see if that is the noise your hearing. Otherwise when my valve clearances were set too loose the car was ticking like, you may just need to adjust yours so nothing major if it's that... however, I hear that noisy valves are happy valves and looser is better than tighter in terms of engine health. I still made mine a bit tighter and got rid of the noise because it would have driven me
. Again, not so sure on the V8 so someone else may be able to give you more on that.
Pulling the oil pan/sump on the m30 is supposed to be a real PITA job so checdk out what the score is on yours before you jump into it... I had a long time leak (only very minor) at the pan gasjet but a few of the bolts had come loose so I tightened them up and I'm going to see how it goes.
3. I think it would be blue smoke if burning oil, black if it's rich and white if it's coolant, but please correct me if i'm wrong. Can't comment on the napa stuff, never used it.
HTH