Steep oolong tea for 3 minutes at 90°C (194°F).
Oolong is partially oxidized, and "partially" covers an enormous range. A green Tieguanyin might be oxidized ten percent and taste of lilac and cream; a dark Wuyi rock oolong is closer to eighty and tastes of charcoal, stone fruit and toast. Both are oolong, and someone who dislikes one may well love the other. The leaves are bruised at the edges, allowed to oxidize, then fired to stop the process — and usually rolled into tight pellets or long twists that open slowly in water. Most comes from Fujian and Guangdong in China, and from the high mountains of Taiwan.
Water at 90°C (194°F) and, more than for any other tea here, room to unfurl. Rolled oolong expands to several times its dry volume, and a tea ball crammed with pellets gives you a fraction of what the leaf holds. Use a pot, a gaiwan, or a basket infuser wide enough for the leaves to open fully. 3 minutes at medium, 2 minutes 15 seconds for a lighter cup, 3 minutes 55 seconds for a stronger one. If your oolong comes as tight pellets the first infusion will taste faint — that is the leaf still opening rather than a fault, and the second will be noticeably fuller.
Judging it on the first cup. Oolong is the tea most often dismissed after one thin infusion from a leaf that had not finished opening; the honest response to a weak first cup is to steep it again, not to give up on it. The second mistake is cramping the leaf. An infuser that suits a teaspoon of black tea is too small for the same weight of rolled oolong, and the pellets in the middle never properly wet. The third is treating all oolong alike — a green oolong wants gentler handling than a dark roasted one, which takes heat and time in its stride.
This is what oolong is for. Four infusions is ordinary, six is common with a good rolled leaf, and each one tastes different: floral early, sweeter and deeper in the middle, mineral at the end. Rather than adding a fixed amount, keep the early steeps near 3 minutes and lengthen them gradually as the leaf gives less. Some drinkers go the other way entirely, using a lot of leaf for twenty or thirty seconds at a time, ten times over. Either approach works. What does not work is throwing the leaf away after a single cup, which wastes most of it.
Steep oolong for 3 minutes in water at 90°C (194°F), or anywhere from 2 minutes 15 seconds to 3 minutes 55 seconds depending on how full you want the cup. Rolled oolongs barely open on the first steep, so judge the leaf on the second or third infusion rather than the first.
It depends entirely on the oolong. Lightly oxidized styles like a green Tieguanyin sit close to green tea and taste floral, while dark roasted Wuyi oolongs are nearly black tea in character, tasting of toast and stone fruit.
Because rolled oolong has not finished opening. The pellets need one infusion to unfurl, so the first cup runs pale and the second is fuller — this is normal, not a sign of poor leaf or wrong technique.
Usually a little, around 30 to 55mg per 250ml cup, though the range overlaps heavily. Oxidation level matters far less to caffeine content than how much leaf you use and how long you steep it.