Summoning is one of the least well defined mechanisms in DFrpg, so any truly detailed breakdown you receive on this board will almost definitely be composed significantly, if not primarily, of house rules.
In answer to your specific questions, a summoning ritual could theoretically be performed from anywhere, but doing so from the location of the target spirit's demise would almost definitely be of benefit (in the form of supplying +2 to the complexity by way of an aspect tag or invoke).
Focus items involved in a summoning ritual could take many forms. Ritual foci for the Ectomancy thematic grouping would be the most probable for the situation you describe. Foci from the Summoning&binding functional grouping would also be possible, but would make less sense for your specific practitioner to be bothering with as they only apply to a relatively small subset of their specialty. Warding foci would apply to the containment of any summoned entity, but suffer from the same failing for your ectomancer's purposes as do Summoning&Binding foci, and possibly to a greater extent.
In short, not only can they be blanket items for summoning (&binding), but they can be blanket items for Ectomancy, which includes Summoning&Binding where ghosts and their ilk are concerned.
