"the understandably frightening and chimeric semicolon" -- HiveGod
Just played my first game of Railways of Europe and love it. Couple of questions:
Baron Card- have the highest level train. In case of a tie, do you still get the bonus?
No. You must have a higher level train than every other player.
When laying track, can I use the track pieces that split off in different directions when completing a line to a new city? If so, does this branching line considered incomplete?
Those aren't branches. They are crossings. Use them only when you are building a link that crosses an existing link: replace the hex where the two links will cross with a hex that preserves the existing link while extending your new link.
You have to imagine the crossings as over- and under-passes. The tracks that cross don't intersect, and you can't make deliveries that "turn the corner" at a crossing.
Later in the game, can you change a track piece on one of your exsisting lines? In other words, make a straight track turn into a track with branching lines.
No, because there are no branching lines.
(Actually you can make branching lines, but only if you have the Railways of the World: Switch Tracks expansion. Normally you can't have branching lines.)