Just starting out…

Just a few questions, as I’m just starting out. I’m considering replacing my WD Live box with a Pi3 and kodi. I’ll mostly be using this to play ISO video files from a connected hard drive. As well as look into the streaming capabilities later on.

How will this compare to the WD and other media players ? Smoothness, ability to handle many video file formats, responsiveness, ect..
Standard TV style remote control ? FF and rewind ?
Ability to play back .ISO files. (to maintain the menus)
Read 3+ Ter hard drives ?

Also, what OS is used for the Pi3/ kodi combination ?
How large of a flash drive is needed ? Speed ?
Power supply ?
Other than a Pi3, kodi, drive, power supply and monitor what else is needed ?

Thanks…