Pressing the tablet stylus button could be making the palettes vanish. Accidentally right-clicking while you're doing a stroke is common if you're not used to using styluses.
Right-clicking again, or pressing 'Enter' will bring all your palettes and panels back again.
DPI you can ignore unless you want to print out your artwork. In that case it relates to the size the printed artwork will be on the paper.
If you have a painting 600 pixels wide by 600 pixels tall, and you set the DPI (Dots Per Inch) setting to 300, then when it is printed it will be 2 inches wide by 2 inches tall. (600 pixels, with 300 pixels in every inch equals two inches)
But during the process of painting, and working with the image digitally, DPI doesn't make any difference at all to the quality of the digital image.
Create your grid overlays as a PNG image - then they'll be perfect quality when you import them as a tracing paper overlay or imported layer.
If you create text in another graphics application - for example Photoshop - you can copy the graphical result to the clipboard, then paste into ArtRage.
And we're always happy to answer questions!
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"