regarding that last part (and tbh i dont KNOW this, as there is information both ways on the forums) (remember the game changed over time so some of those may be wrong / correct for THEIR TIME but may be the same or different NOW) i recomend you enable reinforcement logging and read thru the file, for one of the reinforcement events, from reading it myself it looks like most guardposts (not wormhole GP tho) counts 10% as much as the command station for the amount of "budget" that one star system gets if it is selected for a reinforcement event so this sugests that neutering DOES matter for buildup over time (if you beachead the system however 100%->200% reinforcement size should not matter much), remember these individual reinforcement waves are SMALL since they are very frequent, but for systems you clear rarely i guess neutering matters if the above find is correct (the wiki is no more trustworthy than the forums btw i recomend site:arcengames.com in google as an "extended" wiki)
remember that the reinforcement points are used to TRIGGER a budget income, and then a buy from that budget to turn into ships, it is THAT income that varies based on guardposts. so hypothetically a 10 GP system will get twice as much budget per reinforcement point spent on it IF IT IS SELECTED, no effect if the neutered system next door is selected instead, the budget is used to buy ships as long as it is positve, and it can go negative, but then it will stop buying new ships, and the balance is saved for next time it is selected and it then "pays off" any debt it has before it can purchase more ships so in the long run everything evens out