1) Can English noble blocks retreat from battle from Scotland into England if there are friendly units in England?
2) Herald card: successful play of a Herald card into a space with two enemy units creates a battle.
Is the battle resolved immediately, before the other player resolves Movement? And is the converted noble the attacker or defender?
Speaking purely from recent hours spent reviewing rules and card text I believe the proper answers are:
1. Yes, if England is friendly (or vacant) and assuming Scots did not originate the attack across the border in question I see nothing in the rules that would preclude such a retreat to England. The border from Teviot would impose a 2 block per round retreat limit because it is red.
2. From the text on the card (2nd edition) it appears the battle would be resolved immediately before the other player moves ("If a battle results, resolve it NOW [my caps] with the defecting noble as the attacker".
Hope this helps.