RE: CG for SE5a
For your first flights maybe set it to more like .25 to .27 instead of the .3 suggested by Limeybob. It's likely that the .3 would be fine. But as the old saying goes "a nose heavy model flies a little poorly, a tail heavy model often only flies once". If it's doggy in flight and wants to lift the nose aggresively coming out of a dive or when increasing power it's easy enough to shift the CG back a little and re-trim the elevator. Keep shifting it back a little at a time until the model handles nicely while still retaining some degree of positive pitch stability. You don't want to make it TOO neutral. On the other hand the strong positive stability of a nose heavy model is annoying to fly as well since you feel like you're fighting the nose all the time. Just like the Bear's porridge it's best when it's "just right".