97 Land Cruiser - Need input!

I have a 97 Land Cruiser and I would like to add an alarm and replace the stereo and speakers.  I would like as much input as anyone is willing to give. I have searched here and not found much.

I know that it is next to impossible to find a wiring harness for the 97 Cruiser, so I will have to fab my own and make sure I have all the wires figured out (shop manual on its way to me).  Any tips, tricks or gotchas I should know?

The speakers seem to be a royal pain to replace. No depth. Has anyone done this? What have you done, and what speakers/gear have you used?

As for the alarm, it looks as if someone added an aftermarket, then took it out when they sold the vehicle. I assume the factory keyless entry works and is hooked up, but I didn't get remotes when I bought it. Any issues here?  What alarm would you recommend? Any wiring harness out there to help with this? Or am I in for a splicing event?!?!?

Thanks in advance for any and all input.

Usually I am all for DIY jobs, but when it comes to alarms I highly suggest finding a seasoned installer preferably MECP certified for that particular vehicle. There are quite a few quirks that will throw you for a loop. Like there are 2 wires for unlock both have to be used and diode isolated in order for it to work correctly, the door trigger wire is also very difficult to find. If I remember correctly the easiest spot to get it is behind the cluster. Neither here nor there I would say take it to your closest PRO.  And I highly recommend Viper from an authorized dealer as an alarm choice.