>1- Anybody have VFP6 and VFP8 in the same computer ?
> Does it work nice or VFP8 kills VFP 6 ?

As Sergey said, it works fine. I have FPW2.6, VFP6, VFP7 and VFP8 all installed and working fine. I can share tables as long as they don't have features that are missing in the lower version.

>2- Does refox already protects VFP 8 exe ?

I don't know. Maybe someone else will have something to add.

>3- If I only compile all my VFP 6.0 applications
>into VFP 8.0 will it run OK or do I have to modify them ?

There are some modifications to menus that will not allow you to recompile menus and still share with VFP6. Another thing you will run into is the more compliant SQL language. Specifically, if you have fields in the SELECT that aren't in the GROUP BY and aren't aggregate fields (SUM(), COUNT()) then VFP8 will give errors. However, you can use the IMHO sloppy SQL by adjusting the ENGINEBEHAVIOR setting.

For a better idea of things that have changed you would need to read the What's New in Help for both VFP7 and VFP8. You can also get a lot from the two "What's New" books from www.hentzenwerke.com.