All the tests conducted by the shop do not account for valve seals. Your oil burning issue points right to the valve seals for one reason - It smokes after sitting. When the seals start to leak, they usually only leak a small amount which will not smoke at idle or while driving. However, when the truck sits, the oil keeps leaking which makes smoke on start-up because the oil was not being burned off with the engine running.

Compression checks, leak down tests, and cooling system checks do not count for valve seal sealing since the valve seals are not in the combustion chambers or cylinders. If you had a cracked head or bad rings, that would have shown in those tests. Timing also has nothing to do with it. If you have smoke after sitting, you're burning oil, and you are having performance related issues, you probably need to replace the valve seals. The shop should have pegged that and recommended it.

BG products are phenomenal. I am a user of many of them. 44k is an additive that will clean virtually every single thing it touches, and it will do it safely. I have seen the results first hand, and I highly recommend it. I usually recommend to my clients that they toss a can in the tank every oil change. I don't use the additives that pour into the crank case, but I know many that swear by it. Their intake cleaners and such work wonders as well.

Lifter ticking is usually a sign of them going bad, or you have an oil issue. They are extremely cheap to replace, so might as well just do it. I use an engine flush additive just before changing out lifters in an attempt to clean out oil passages before the new lifters go in. Its up to the end user though.