A 160
Yes. You can combine a touch spell which you're holding the charge with any kind of bare-handed or natural attack. An unarmed strike, a grapple attempt, an unarmed trip attack, even the "blind reaching out over two squares to find out if there's an invisible enemy here". As long as you touch an opponent, it discharges the touch spell. A vampire slam attack is no exception, and both spell and energy draining will be combined.