Howdy CJB, glad you got that registration problem solved and Welcome To the Guild, The Mappiest place on the web.

Now back to subject at hand...
I like the layout that you have and am iterested in where you take this. As for the number of rivers, at this scale (global) there are VERY few rivers that can be seen on a satellite image of earth. You are more likely to see the mouths of large ones, and maybe the effects on the land, but not the rivers themselves. The rivers you see on maps and globes at similar scales are just lines to indicate the location, not an indication of width, of the river. And YES, I agree that you should figure out the mountains and other land features before placing the rivers. Then place vegetation...

Tectonics is handy, but unless you need things to be just right, I don't think they are a requirement. Some people want their world to fit with reality and such, others not so much. They are definitely NOT required to make a great map. There are many great examples in the Finished Maps section that never looked at tectonics, just like there many that have. Just choose your poison Understanding tectonics can help you understand where to better put your ranges and your weather patterns, but you don't need to be a slave to them.