Yes only Generals have access to Priests and other minions. Its kinda why they are called... Generals. Assassins get plenty of Mcstabface instead.
Here are stats on priest heals - the Sedna buff is the increased effect caused by Healing Winds Rank 2 (which is damn tasty).
Monk Minion / Priest Reinforcement
200 health to non-demigods.
300 health to non-demigods when buffed by Sedna.
10% of max demigod health.
15% of max demigod health when buffed by Sedna.
Priest Minion
230 health to non-demigods.
345 health to non-demigods when buffed by Sedna.
12% of max demigod health.
17% of max demigod health when buffed by Sedna.
Bishop Minion
260 health to non-demigods.
390 health to non-demigods when buffed by Sedna.
13% of max demigod health.
30% of max demigod health when buffed by Sedna (yes, this is a bug and Bishops heal for more than High Priests when buffed by Sedna).
High Priest Minion
290 health to non-demigods.
435 health to non-demigods when buffed by Sedna.
15% of max demigod health.
22% of max demigod health when buffed by Sedna.
Source: http://demigod.wikia.com/wiki/Priest_Healing