Elf trance vs Human sleep


When casting Temporal Shunt at 6+, if one of the additional creatures is concentrating on a spell, are they able to maintain concentration through time?

PC has Helm of Comprehend Languages. He wargs into his familiar Owl. Owl flies ahead, sees writing in Infernal. Can the PC read that via the Helm?

Do the Frostbrand and Flame Tongue swords not get a + anything to hit/damage?

Ranger Multiattack defense, does the AC +4 bonus also apply to multiple attackers who hit you in the same round?

Can a caster use 2 spells in surprise round with the ready action?

Are Booming Blade and Green-Flame Blade compatible with extra attack?