I have iOS app also. LG TV Plus sucks after last update. If you want, you can try previous version - LG TV Remote-webOS. It's more stable and keyboard works better in it. Just download and install via iTunes.
About YouTube app - keyboard doesn't work in it, because It's constructed in such a way. But you can use YouTube app in your phone to search videos and playback them on TV.
04.45.25 is latest official firmware, but you can try webOS 2.0 BETA firmware(install via USB flash drive), or just wait September 21st when LG planned to roll out official WebOS 2.0 for 2014 models..