Ask HN: Hackathon Presentation Software/Hardware

I organise a hackathon and need to plan the presentation and other visual stuff.

I really hate it when the transition between presentations is not smooth, how can i solve this (cheaply, i have an raspberry-pi left if it's helping)?

Also i need a fullscreen-countdown, all the websites popping up are not stylable. Ideal would be the ability to place a logo above the countdown.

An real-time schedule-overview would be nice, needs to run on an rpi since i need my laptop.

Any other suggestions?