Harris cyclry has a page for looking at gearing. I was playing with it using my bike's information yesterday to get a better understanding of how my bike works. I have a K2 Zed 1.0, which means the front chainrings are 24, 34 and 42 teeth. The cassette in back goes from 12 to 32 T. Turns out that several of the gear combinations I use frequently are almost identical *g*.

After all my playing around, I've concluded that if I can build strength and endurance so I'm mostly riding in the toughest gear (42/12), I'll probably have outgrown the gearing on my bike some. I won't have a bigger gear to use for building more strength. So on a new bike I'd want the biggest chainring to be bigger, and to cut down on the number of not very useful gears.

It might be worthwhile for you to play around with your hybrid's gears with their tool. You might find that you have a lot of gears that are really the same, or that you have gears that are really bad for hill climbing. You can even compare the gearing you have to my bike, or to bikes you find online.

I can't really help on the other questions. But if you understand how the gearing you have works, that might help you with buying a road bike.