If Bruse Tarl leaves the battlefield after other Oxen you control have dealt first-strike damage but before regular combat damage, those Oxen won't deal regular combat damage (unless they still have double strike for some other reason) .

Bruse Tarl's ability doesn't allow you to play land cards that it exiles. But hey, free Oxen.

You pay all costs and follow all normal timing rules for spells cast from exile with Bruse Tarl's last ability. For example, if you exile a creature card this way, you must wait until your main phase to cast it.