How to submit a talk to a conference – Starting with replying to a Call for Presentations I have received a Call for Presentations for a conference and I have a topic that could be interesting to present.

The Call for Presentations describe the various forms of presentations that one can submit, and then links to a form asking for a title, presenter name(s) and an abstract. This has a deadline around two months before the conference.

Now, to my questions: As I mentioned, I have a topic in mind, but unless my presentation is accepted, I would prefer not spending a lot of time preparing a good presentation of this (technical) subject. Will the decision about whether to accept the presentation be done solely on the grounds of the submitted abstract or will they be in touch before accepting the presentation?

(This is a computer science conference, in case that's germane.)
It depends on how close you research topic/presentation is to the conference topic. I've never had an abstract turned down, but I present in sessions with topics relevant to my research. Most conferences wan't people to come and present, in general. Worst case scenario, it get's turned down. You will have a head start on the next abstract submission.