I hope 4.55 is cracked soon (quite likely, according to the recent "to be released next month"stuff) so that we can install them on the external HDD like we could do forever with the Xbox One.
btw. i found some info as far as the biggest drive you can use, which is 8tb. when you plug it in and let the PS4 format it will in fact use it as one big drive (not the for-mentioned concept of having to have it in 3 partitions and 1 extended). if you want to use the ext hd as extended storage and be able to install packages and run them from the external, of course this is only AVAILABLE on 4.5 fw - but that is close to being released now
here is the video on how to use a new 8tb external HD
Hope this helps some people. I know when the 4.5 exploit is released i'll be using mine!