The yokahama y356's (185/65/R14) I have on the van say max pres. 65psi.

Should I inflate them all the way to 65psi all the time, or 
maybe just when I'm fully laden with all god's creation of cargo?

Right now they seem perfectly happy at 42psi.

What about any recomendations in the owners manual?

do folks mostly just inflate to the max pressure on the sidewall?

What about inflating the rear more than the front?