[Cronos]

Valid question -- we do believe that God would allow them to hear us, but they have no omniscience or ability of their own, it is God's grace.

Heaven is truly a mystery for us as you say. For me in particular, I don't spend much or any time doing that speaking -- I commune with God in prayer and in the Eucharist and as a Catholic that's good. Requesting saints to pray with you is additional praise to God.

[Siena Dreaming]

we do believe that God would allow them to hear us, but they have no omniscience or ability of their own

And why would you believe God allows them to hear you...just because you want to or the church tells you so?

One has to have personal contact with a saint on earth to communicate but a saint in Heaven can hear any prayer directed at them at any time? Sounds suspiciously like omniscience and/or omnipresence to me.