Once an agenda has been scored and moved to the score area, can you then install a new Agenda in the remote server the former inhabited?

Sure! you has to spend actions advancing the agenda, once that you get enough advancent tokens (note that you can advance it more than the requeired advance points if you like…) you can score it and put in your scored area. Then your remote server is empty and if you already have actions to do it, you can install another agenda/asset in this remote server.

I hope have clarified your question. :-)  

Thanks! That does indeed clarify that point, though I've another query now.

Once an agenda has been scored, can one still activate it's abilities? For instance, Private Security Force's 'Spend a click to deal 1 meat damage' deal.

Well, you can't use it's abilities otherwise, so after their scored would be the only other time possible?

My train of thought exactly. Just trying to settle something with an associate.

Ignatz_Von_Zwakh said:

Agendas are considered as "active" just only when are scored, and this efect is permanet while the agenda is scored. This mean that ever time that runner is tagged during your turn when you have Private Security Forces scored you could spend an action to make to he/she one met damage. (three acctions, three met damages…so yes, is a bit dangerous to be tagged when the corp has scored this agenda…) 

But note that several agendas has the text of "when is scored", this effect is not permanet as Private Security Forces and the effect it is only triggered in the turn that agenda is scored and no more.