'93 Camry; engine noise and RPM questions

[Vibroseis]

I have owned my '93 Camry LE V6 for about 7 months now, and there seems to be some engine noise developing. The noise is mostly noticable during fresh starts (after aprox..10hrs rest) and intermittently present at idle. The noise sounds like a tapping sound. The car currently has 132000km on it and according to a note in the engine bay, the timing belt was changed at 77000km. What could be causing this engine noise and how to fix it?

My second question is regarding the engine RPM level rising during drive mode selection (Park to Reverse, Drive..etc). This is probably commom on many Camrys, but why does this happen? Is there a way to get rid of it. The rise in RPM produces a big jolt everytime you make a gear selection. This can't be too healty for the transmision for the long run.
Thanks. Your input is appreciated.

[Silver Streak]

That's a pretty hard thing to figure out...could be just noisy lifters, you can try adding some engine additives to quiet them down.

Sometimes a cracked exhaust manifold will make that sound and once the engine gets a bit warm, it'll stop making that noise.

But it could be a lot things...hard to tell over the internet.