Spee will have intended to form landing companies out of his ships’ compliments, as per Emden’s raid on the Cocos Islands. With no naval battle anticipated, a ship like Scharnhorst could easily contribute 200 men, for example.
Specialist landing parties would be smaller, but the sailors were trained with small arms iirc, so finding a force was not a problem.
IMO, there isn’t a chance Spee was going to do anything but make a smash-and-grab raid lasting at absolute most a few days.
Probably two days, he was not really lacking coal at this point, but had disposed of some of the merchants at Valparaiso and now lacked the ability to carry as much with him. It would have taken enough of a day to take any coal needed, and then to fire the rest and the radio station, but to imagine an occupation by a force of reservists who must be short of arms at best, and of food within a short time of any occupation starting, is heading off into fantasy to my mind.
Such an operation would have been possible if given prior planning, but without that, and no obvious sign of any secret signals or who made them, I cannot see that it was ever contemplated in 1914.