Lear 28/29
 

What is the current status on flying Leat 28/29 on N-reg in Europe ?
Noise ?
Suppose RVSM and TCAS 2 are installed
What is the max range of a Lear 29 ?

Sorry, but I can only answer one of your questions, the range.

It is short, with legal IFR reserves don't count on more than a 1,000 Miles. If, and it is a big if, you can get an unrestricted climb to FL 47.0 or higher.
Another way to put it is that in the best conditions you need to be on the runway in less than 2 hours after takeoff.

One night I was coming back to Oklahoma City (KOKC) from Washington National (KDCA) which is 1006 nm. Due to high head winds and low ceilings all over the area, barely above minimums to below minimums, I had to stop twice for fuel.

The closest alternate to KOKC was Amarillo, Texas, which is 200 nm. The second fuel stop was at Springfield Missouri. We had enough fuel after taking a full load to takeoff, climb to FL 51.0, descend and shoot one ILS, if we missed to climb back to FL 51.0 go direct to KAMA and land with around a 1,000 pounds of fuel left, which is about 45 minutes at best. The weather at KAMA was clear.

Oh, we made in on the ILS at KOKC. (I still to this day swear we really did have the approach lights at minimums, really.)

Now the Lear 28/29 is not all that fast, .78, and has a really poor range, but it can climb like a bat out of hell.