Factory Alarm

[igotnothin]

I have a '91 LS400 with a master and valey key. However the button and spring on the master key were gone when I purchased it a few months ago. I've simply assumed that I don't get keyless door entry nor alarm.

One day recently I locked the door with my key (on the driver side), while leaving the driver rear door open to get my kid out of the car seat. It took a little while, when all of a sudden the alarm went off. I was so surprised, that at first I thought it was the car next to that was going off.

I can't replicate the event. But I'm now thinking that I just may have a factory alarm, even keyless entry if only I had a key w/ a button.

Questions:

1. How easy is it to get a new key w/ button?

2. Once I have the button, will the keyless entry/alarm work?

3. Is the factory alarm good enough?

4. What about installing a non-Lexus alarm on it? I have a decent Python alarm on my old car that I feel is still good enough that I intend to keep it once I replace it (esp. since I spent > $500 on it. Can I throw that in my '91 LS400?

5. If not, any recommendations as to what a good non-Lexus alarm would be?

6. Is the button on the key for both the keyless entry and alarm like I think it is? If so, and I install a new non-Lexus alarm, can I somehow get that programmed to take the signal from the factory key? I intend to get the new key for the button if answer to #1 & #2 are "yes." And if #3 is "yes," then I'll need a new alarm.

Thanks in advance!