Perhaps enables a g15 module?
And the -dev is just enabling developer mode, like Nut has said. It shows debug messages on the top left side of your window, here's an example:

I leave it on mostly to know when I'm stuck somewhere. It shows something like "Client stuck on object id xxxx"
I use:
-novid -console -dev -window -noborder
I can guess what window and noborder might do, but what about dev?
-window -noborder creates a 'fake fullscreen' mode. I have two monitors and that helps a lot with alt-tabbing, plus it looks better than just windowed mode.
I've also read that you don't want to use a heapsize greater than 1/2 your total memory.
Heapsize is just the caching memory for maps and objects. It doesn't include the working memory the game needs. I haven't changed mine and I suspect the default is 512mb.