Regarding color, with Pine you should add some color. It does not color
as well as some other woods over time and some varieties go white to
gray. You can try using a Natural Oak type color. Very suttle but ads
some nice warmth. I assume logs with have uneven coloring, just like
Pine boards so you should use a pre-stain or sanding sealer before
straining. Also, prior to that, if you are going to color it, wipe it
with Mineral Spirits, this will show you the sanding irregularities
that will show up with the stain and giove you an opportunity to smooth
them out befor estaining.

I think any film finish would be good. Not Tung. Varnish oil could be
ideal. Or even just sealing with very few coats of wipe on poly. What
ever you do, I'd do just a few wash coats (thinned), cause you really
don't want any gloss or plastic look to you logs.

Depending on the look you want and the details of the design, I did a
pine project, used minimal color stain (maybe Ipswitch or Antique can't
recall), then I used a dark brown glaze paint, painted on and wiped
off, just leaving it in the cracks and grain lines. I did very little
of a very thin wipe on poly and then waxed it to a low luster. One of
the best finisheds I've ever done. Problem was I did it perfect on the
sample but put to much poly on the final piece.

Live and learn.