As for the gauges, if you don't already have it, go get CfgEdit.  Its a panel editor that places gauges on the bitmap for the 2D panel visually.  It can also help you with the VC, but it isn't set up for FS2004.  It can't handle the new XML gauges, but you CAN use it.

For the tutorials, go to www.freeflightdesign.com and look in the tutorials section.  There is a specific tutorial that teaches you how to create and add VC gauges with visual clues.  It won't teach you how to use CfgEdit, but that isn't hard to pick up.

MS Paint can be used to create textures, but it really, really sucks.  I would recommend you go out and find a good paint program.  Many people prefer Pixia, since it is freeware, but you could also go and download the free trial of any good paint program (I use Paint Shop Pro 8.0) and then use it for the trial period.  If that doesn't do you, then Pixia will probably be your best  bet.

For painting, you might also want to look into reflective textures.  You'll find plenty of tutorials at the FFDS (Free Flight Design Shop) that deal with reflective textures and adding them into Gmax, or making them for other aircraft.  For this you will need DXTBmp, which is a freeware program that converts the textures into the format FS can use.