So I shoulda just sent 1 arc instead of 2 at that adjacent plant. :/
In the long run, it doesn't really matter. Probably arguments to be made for both sides. As your first planet, I guess when it matures in 50 days it'll be nice to see it has a decent sized population.
Do they absolutely need escorts?
Not really. Escort them if you're going close to someone hostile, but generally you're fine.
Also, should my merchant ships be with my arcs and with my war ships?
Arcs: nope, no need, other than a bit more population or to instantly try and buy up some steel to bring home. Military: maybe, if you're sending them far away then it might be nice to have an escort, but for internal trading between your own planets (and perhaps with a close neighbour, like Sacha) then nope.
