Both are true! At level 55 you can zone into PoV, however you will not get an AA or a charm upgrade. Once you complete a PoJ trial you are "flagged" for PoV and will get a free AA and charm upgrade.
A cleric should be fine for PoV as soon as you can zone in. Be warned though, you will get a wide variety of quality in tanks in PoV - A 55 tank would be very hard to heal, compared with a 65 tank with hundreds of AAs (the exp in PoV is decent enough, even at 65 - I group there myself occasionally). The mobs here hit much harder than anything you will have been used to so far.