Are clinch knees the same as stand-up knees?

No. Different input, different job. Stand-up knees meet an entry. Clinch knees are the damage while you hold the head.

Should I throw hooks in the clinch?

Rarely. They do not turn. Knees and elbows fit the space.

You are hitting a high block or you do not have the tie. Change position, then throw two.

In a lock, short shots win. A wide hook from the clinch is almost always worse than a knee or an elbow.

How to strike in the UFC 6 clinch: knees, elbows, and short punches — and why long hooks die in the lock.