Mike - my 2 cents...

1) Unless you intend to use a two-part linear polyurethane, the varnish is going to impart an amber color, and the wood darkens somewhat from sunlight, even with the UV inhibitors in the varnish. Spruce and pine are both light, but my experience with spruce is that the growth rings are often a different color...not sure about pine. I like Alaskan yellow cedar (same as pacific cypress) for a nice, consistent yellow color, and it is a good boat-building wood. I, too, would like to find something that is white, and stays white.

2) Are those my only choices? I, and a lot of people here like RAKA, with the 350 hardner. Less expensive, good wet out, no blush. Check the archives for RAKA - they also sell supplies and fiberglass at decent prices. And Larry is helpful.

3) Can't even give an opinion!

Good luck!