If you are feeling adventurous you could try a light green shadow with dark forest green eyeliner to accent your eye shadow.
As far as foundation goes, I would wear whatever you feel comfortable wearing. You can buy a sheer coverage foundation that will somewhat hide your freckles, but not look thick or “caked on”. Foundation basically is used to even out your skin tone and cover any imperfections you may have on your face. If you feel more comfortable with just powder then you should go with that option.