Hi - good questions... personally I use ADX only as the entry signal, for when it gets >40. For volume spikes, "it depends" as sometimes it's an exhaustion/pivot by the time you see it, other times it's a signal of a continuing breakout.. which is why tape reading is needed for identifying the buy/sell imbalance, along with price elasticity/range.

In general I am skeptical of any strong move continuing for longer than 20 minutes or so for an intraday stock breakout.

-ken