I know, my wordcounts are regular monsters. I blame my touch typing speed being well over 100 words per minute; my fingers fly faster than my brain a lot of the time. Much gets shed in the editing process though. (Quality, not quantity. I had to learn how to write good short form just like other people have to learn to get used to long form.)
As for a plan, I think it depends on the idea. My very first I went into with no idea of where it was going, wrote straight through to 50000 without really getting stuck and it turned out to be my favourite writing project ever (Still is). The next year, I went into it with the plot vaguely mapped out and that went fine too. The year after, I didn't have a plan and the idea just completely fizzled out. So last year, I planned down to what would happen in every 5000 word block. It got me there but I loathed the writing process. I guess it depends on what kind of mind you have but I'd certainly recommend having a loose plan, not a strict one. That way you still feel like you're creating along the way but you don't get stuck.
"Does the Walker choose the path or the path the walker?" -Garth Nix
(Av/sig by Amy!)