The best free solution is CoolSoft VirtualMIDISynth.
Try these specialized databases (always scan any downloaded file with antivirus software): Download Soundfont Sule 2
A: Not directly. GarageBand does not load .sf2 files. However, you can convert the SoundFont to a Sampler Instrument using the free app “Soundfont to Sampler” on Mac. The best free solution is CoolSoft VirtualMIDISynth