Regarding Mary being dead ... she is alive in Heaven, as we all seek eternal life with our Lord and Savior.
Throughout scripture, praying for the souls of the dead and departed is status quo. Asking those we know are in Heaven -- like Mary -- to pray for us is Scripturally based. If I can ask you to pray for me, why can't I ask Mary to pray for me? We don't pray TO Mary, we ask for her intercession, as well as all the saints in Heaven. In Revelation the Holy departed bring our petitions and prayers to God the Father. And, if you have listened to a Catholic prayer for Intercession, they all end with "In Jesus name", because ALL prayers are addressed to God through His Son Jesus Christ.
God bless.
My point is gop unless you elevate them to gods..they can not hear your prayer