I have some questions about the game because im a newbie

for example: im really bad and am currently learning first how to build my civilization up before learning to fight, so i've been playing tiny/medium/small maps, having one person (npc) playing with me with they're intelligence set to fool and them as my ally so they dont attack me, then i build a civilization, research basic military stuff (weapon theories, planet invasion, starbase defences, wall the other person in so they cant develop then
I develop, colonizing and building on all the other worlds etc. i just dont know how to make an npc that was my ally my enemy, i cant find the way to do this. help would be appreciated. also, i was wondering, is there a mode where i can play without any opponents at all? just so that i can practice building my economy. and on modes of play is there a way to toggle minor races? also, i want a mode of play where i start with the very basics (planetary improvements, xeno research, diplomatic relations, universal translator, all weapons theories) of technology so that it doesnt take me forever to build up. any help would be great

thx!