To most of your questions, Yes.

Trolling has many applications. Minnows, with and without corks, and jigs and cranks. Pushed with weights and pulled longline. The best i can tell you is to be careful and patient when buying equipment, as some can be technique specific, but others will lend to several ways to troll. I started with 12' rods and haven't varied much since. Others use longer and I can't argue with them, it's just what works for me.

Rod holders is another argument that will get some mileage. I use and prefer Hi-Tek Extreme rod holders after trying others that fell short for one reason or another. These are high sided which lets you troll with the rods 90* to the boat like I do without having a fish pull the rod sideways in the holder. All aluminum and a half inch wrench to do all adjustments. I tried knobs and got my line hung up now and then. Gotta be smarter than what you're working with. Lots to choose from.

While baitcasters work well for cranks, I think that spinning reels in the 2000 series will do a very good job for most any presentation you would choose. Hi-vis 6lb line in a big spool will last a long while, but I prefer 8lb for trolling cranks. Cheap in the store brand at BPS.

How deep and how fast is determined by the fish. Spider rig anywhere from .2 to 1.5, more weight needed the faster you go. Cranks from .7 to 2.0 mph, and there's combinations of the two used together.

Suffice to say that all you need is a desire to try something new and get after it. Ask a question, watch a you tube video, or bother someone at the ramp like I do. Start moving and throw a line over the side, you'll be surprised what goes on after that.