Do you shoot on raw?
Yes! I do shoot in RAW. I would really suggest for you to do this as well. My preset packs are really geared towards RAW images. You have so many more options and so much more freedom when editing a photo that was not shot in JPEG.
Will i have to tweak them?
Soooo as with all presets, you may find yourself having to tweak these to get them just right. After I apply the preset I find myself sometimes adjusting exposure, temperature and HSL sliders. The reason for this is that different lighting situations and temperatures effect how a preset functions, so it is up to you to find the perfect match to fix it up.
Do you ever shoot under/over expososed?
When shooting I try my best to exposure true to life. I try to get the color and exposure as close as I can to the real thing. However in some situations I do under expose to save some highlights and not lose detail!