1. Yes, much shade will limit production. Growth will be uneven and fruit will be small and ripen unevenly.

2. These pruning instructions, from an organic grower in Maine who cultivates 2,000 high bush plants, are among the best I've seen:

"Pruning - During years one to three, encourage roots by removing only broken branches and weak growth; and remove most flowers for the first two or three years. To encourage upright growth, remove branches that grow along the ground.

In years four and beyond, a mature bush should have six to 12 canes ranging from one to six years old coming up from the ground. Remove weak, fruiting shoots and anything in excess of 12 upright canes. No individual cane should be more than six years old, since older canes are big, tall and mostly vegetative with very small fruit. Canes about three to six years old are most productive and have the best fruit.

Prune in late winter, when plants are dormant, as soon as you can get into the planting – commonly in March, although the first of the year is fine if the snow is low enough. Fall pruning can break dormancy and increase winter injury. Even if dormancy isn’t broken, fall-pruned plants tend to flower earlier, subjecting more of the crop to frost.

With loppers, remove one to four of the oldest (tallest, thickest) canes that are over six years old. Cut them to the ground, unless the bush is producing few new shoots. In this case, “stump” the plant by cutting it about 8 inches high. Breaks from the stump will create new shoots. This practice is frowned upon farther south, because it promotes a crown rot; but that disease is not a problem in Maine. Stumping can work well with a variety like ‘Patriot,’ which doesn’t produce many new shoots; most varieties, however, produce lots of new shoots.

Then thin new canes, leaving one to four of the most vigorous; these will replace the old canes.

Next, in the canopy of the plant, use hand shears to remove shoots with weak growth (under 6 inches long and with few or no fruit buds). Remove winter injured shoots, which have chocolate-brown colored buds. Keep strong shoots that have a good balance of flower and vegetative buds. (Flower buds are teardrop-shaped; smaller, pointed buds are vegetative.) Remove 50 to 75% of the fruit load from the bush, since blueberries habitually over-fruit, which decreases fruit size and quality; delays maturity; and can set plants up for biennial bearing.

Renovating Neglected Bushes - Neglected bushes can be cut down with a chainsaw. Old, established plants with good root systems will send up new shoots, and three or four years later, the plant should set a good fruit load.

An alternative is to remove one-fourth to one-third of the oldest (biggest, thickest, tallest) canes with a saw every year for three or four years. At the end of the fourth year, some four-year-old canes will be producing."

Huge appreciation, gardengal48. Very valuable & detailed info.