Crafty360,

1 - Yes, it's OK to ask questions here, especially if you have familiarized yourself with all the information available on this website and forum, which you obviously didn't, because then you wouldn't have asked most of your questions.
2 - Yes, SH3D can make a 3D visualization (photo) of the kind your customer requires.
3 - Yes, you can very precisely follow current or new measurements of rooms.
4 - Yes, you can change or adapt colours, textures, etc, because you can define colurs on an RGB basis and you can import and apply your own textures for wood, tiles, etc.
5 - The learning curve is definitely shorter in SH3D than in Sketchup. Your first picture would take you anywhere between 5 minutes and 5 days, depending on the level of photorealism that's required.

Now, I suggest you first do the following things:
- watch the video tutorial
- view the examples on this page
- view more examples in the gallery
- view these examples and download and study their files to see how it's done
- read the manual
- read the plug-in manual
- download and install version 2.6
- download and install the Advanced Render plug-in v1.6

Good luck!

Hans