There is over 60 Safari related threads in this forum, many of them applying to iOS8...
Regarding lookups, I'm noticing that when I'm participating in the MacRumors forums, that Safari is a bit wonky under iOS8. The flashing text insert marker sometimes finds itself outside of the text box.
And the big issue is that if I start erasing text by rapidly hitting the delete (x) key, on occasion Safari will freeze. The way to correct this is to switch out Safari to another app, leave Safari running in the background, and then re-select Safari from its launch icon. This unlocks Safari and if I'm lucky my reply is still sitting there waiting for more editing. If unlucky, it's gone.
For this issue, a restart of Safari or the iPad has not required.
For Apple feedback see: https://www.apple.com/feedback/
Safari issues send bug reports to: https://www.apple.com/feedback/safari.html