John,
Trolling is a lot of fun.
The best thing to do is to find the newest version of Precision Trolling Book, it will be your bible for a few years.
There is no “best” line but I would recommend you stick with things that are considered baseline then branch out from there.
Most diving curves use Trilene XT in 10# test as the “gold standard” line. It’s tough and works great on linecounters to boot. Some lines have more or less thickness than Trilene XT 10# which can affect the diving curve.
I set my Daiwa 27 to Zero then put on about 2/3 of a spool of 15-20# line as backing. At the end of this I tie a loop knot. Then I tie another loop knot in the 10# Trilene big enough to go over the whole Trilene spool. These two knots won’t break and can be done in about 20 seconds total.
From there run 10# until you almost reach the edge of the spool inside the linecounter. The first time out or in your driveway run off about 200′ right away and reel it back in nice and steady under some pressure. You’ll spool will be filled about perfect.
I’ve used Cajun Red (Shakespeare), Bass Pro (supposedly Stren), Cabela’s (Supposedly Shakes), Trilene Big Game, Silver Thread, Stren, YoZuri, etc., over the years.
I can’t say any of them have really disappointed me, they all have their pluses. I just seem to always have 100 spools of line
My suggestion would be to get comfortable using Mono then start going with Fireline, again in 10# test to gain the dive advantage and “showability” at the tip of your rod. Superlines will help you watch your lure run correctly. The same loop knots will work but fill your spool about 85% roughly before putting on Fireline. I like to get on about 450′ on a Daiwa 27. That way if I lose line I have about two back up lengths.
My best suggestion is to buy matching rods. Buy 2 of everything when you buy and match up things for each side of the boat.
Good Luck