Most of these templates (used for conference presentations) don't come up correctly:
These are templates made for Powerpoint and they work reasonably well, when using (Classic - Windows and Mac PowerPoint) here. I may suggest to have a look at the LibreOffice template repository http://templates.libreoffice.org/template-center.
PS: This is a question which came up: Why are you not using Draw [or MS Publisher] for creating a poster. I got confused by very wide posters, as they can't be displayed via a projector. Draw is better for your purpose (as far as I got the point)]
Actually they come up terrible/unusable. Yes I realize that there are LO templates available for presentations (not posters that I know of) but I don't control when a scientific conference requires a poster made from a PPT template. It's kind of like going to a foreign country and suggesting they all speak your language instead of you trying speaking theirs. So unless you are suggesting that practically every scientific and engineering conference also support LO file formats (which I'm not opposed to) up front, LO/OOo users will be out in the cold.
As to latter question. These are poster sessions that are large print-outs where researchers stand in front of posters during the session and answer questions. You will find poster sessions at pretty much every level and type of scientific/engineer discipline. They standardize on PowerPoint because it can handle large formats and most users have it, requiring something else would add $ burden and learning curve. If you give presentation usually separate ppoint slide deck is also required.