I think the guiding question between your first question (internal versus overflow) really depends on your space and where you are putting it.
If you have extra room to set the tank 6-9" or so from the wall, then go with an externally plumbed, coast to coast with a bean animal. (see previous advice about whether you or someone else should drill it).
If space is a consideration, go with an internal reef-ready tank, as not having all the space behind it is the advantage to that design.