I mark mine with a black dot so I can use the concave starter like Grenadier, and keep them centered better. That way I don't have to fumble for my 'reading specs' when on a trailwalk.
The new Lee molds don't leave much, if any, sprue. If the sprue bothers you then I'd suggest getting a Lee mold.
I always shot the sprue up, its how I was taught. But I rarely shoot round ball in a smoothbore. I don't think it's as big as issue in smoothies.