There 2 oracle centres in reading oracle one is the shopping centre, which is ok other than the rediculous parking charges. And the oracle business centre (with the red writing you see as you pass it on the train) they are part of java x
Jct 5 or it's not even a junction on the welsh end! Think it would be 49 - it's the second roundabout on the m4.
About 2 mins from each junction depending on work!
I must cover the longest stretch of M4 surely lol