No, mana regeneration is only affected by armor/meditation, tabbing out of PvP situations is usually used to 'ready' an attack. There's a few other reasons you might want to tab out in combat, but it's somewhat situational. More space, multiple homes, can hold unique events (i.e. CTF), and it's a pretty unique feature to go between two houses. All of these reasons also increase the value of homes. Because the overlapping area between two towers can be bridged, and if players can do something, changes are they will do it. Ultimately it's because of the housing rules that Telamon implemented on the shard, some shards do not allow bridging, while others do.
Stun punch, disarm, or even readying an attack to hit when you land a spell. PvP is mostly about burst, if you can do 100 damage over a few seconds, you're almost guaranteed a kill. Not sure about the archery question as I've never played an archer here, but my guess is that your hit chances are definitely higher, and your chance to be hit is lower.
