[Turtle91]

Yes, SVG images can be used - I use them all the time. Having said that, some older devices may not play nicely with them, so check your target device for compatibility.

As for the errors, some software might be adding metadata attributes that are not in the "standard" or that the checker software doesn't recognize. Either update your checking sofware, or just remove the metadata attribute manually. One way you can do that is by clicking on the svg file within Sigil, then finding/deleting the offensive info.

edit:
I also make sure I remove any extra metadata when I save an SVG using inkscape...just select/deselect the appropriate boxes in the save dialog. ( I use Optimized SVG) I'm sure there are equivalent options in other software.