IIRC, JayzTwoCents or ScienceStudio or LinusTechTips have a fan guide on youtube. If I'm unable to reply, please check them
This is a good option for air cooling. But if the bottom lacks enough clearance, it'd be better to use two front intake and 1 each for top and rear exhaust.
Make sure all fans have same operating speeds to maintain balance otherwise you'd end up with excessive dust buildup. Align the CPU cooler's fans to push air upwards (probably most effective with bottom intake and top exhaust) or backwards (effective with front intake and back exhaust).
I guess you already have a case fan. Could you share its specifications? Matching fan for output and speed would be good for airflow I think.