Ok, this is how you would do it:

I am assuming that you have already done some minor modding already and have already have converted data... if you haven't tell me I'll put the instruction.

Ok, once you have your data ready, open the home planet enetiy file and go to the section (you could do the same for metal section also)
    crystalResourceAsteroidSetup
        minCount 2 -> change this to 15 or 30
        maxCount 2-> change this to 15 or 30
        extractionRate 0.500000 -> per asteroid per second
        refineryRate 0.060000 -> per asteroid per second
        maxRefineryCount 6 -> also change this to increase the number of refinary ships you can have per asteroid

As for people look for the last stage in your path:Population section, what ever you do, make sure the last one is 3000 or else (say if you have 3000 then the last one is 100 it will reduce your population from 3000 to 100)

change the last stage maxPopulation 500.000000 or whatever value you have to maxPopulation 3000.000000

as for tatical modules same thing, find path:TacticalModules and in the last stage change from maxModuleSlotCount:Tactical 40.000000 or whatever value you have to maxModuleSlotCount:Tactical 200.000000

as for alligence, you need to open your gameplay.gameplayconstant, find the planetData under

        allegiance 1.0
        allegiance 0.75
        allegiance 0.75
        allegiance 0.6
        allegiance 0.5
        allegiance 0.5
        allegiance 0.3
        allegiance 0.3
        allegiance 0.2
        allegiance 0.2
        allegiance 0.1
change the first one to 2.0 because the first one will define itself as the homeworld

edit: and as for etc, you got to list out what you want to change, but mostly use the dev program to fiure what you want to change, and most of all play around with the files the worst you can do is crash the program

Instead of increasing the number of asteroids perhaps increase the rate per asteroid, as this will not result in an empire tree full of asteroids. As well if you are going to increase your homeworld resource rate by 10 (3 asteroids to 30) you might simply want to increase the tax per pop rate by a factor of ten rather than by increasing the population to 3000 as this will take ages to get back to if your HW is bombed (of course you could increase the growth rate of the population).