I was wondering if the removal and installation of the rack and pinion on a lexus 1991 ls400 can be performed in my garage? Is there a tutorial on how to perform the job? And if there any other things I have to look for while I do that process, like hoses and other connections that need replacement.

You should be able to. You can get a Haynes or Chiltons manual for about $15. I would replace the outer tie rod ends while at it. I would recommend a small pitman arm puller ($12) to remove the outer tie rod ends instead of a pickle fork.

Don’t forget to get and use safety jack stands weight rated for your vehicle.

Maybe you can but normally it requires the front end to be off the ground with both wheels off. Not something I would want to do.