1. What do other religions think the 144,000 are or is?
Most do not focus on this at all. The book of Revelation is heavily symbolic and hard to interpret. Most denominations don’t derive theology from the symbolic parts of the Bible and then reinterpret the non-symbolic parts, rather the other way around.
Watchtower theology picks at chooses what parts of the 144000 to take literal and what parts are symbolic. For instance, twelve tribes of Israel? Symbolic. 12000 each? Symbolic. So a symbolic number (12) multiplied by another symbolic number (12000) ends up being a literal number (144000)? The 144000 are virgins, but Watchtower says that is symbolic? And where does it say only they go to heaven?
If you do a little digging into the “Great Crowd”…that they are shown performing Sacred Service day and night in the Temple (the Holy Place, not some outer courtyard), then it is obvious they perform priestly duties and are part of the “kingdom of priest and a holy nation”.
Also if you do a little digging into the “Other Sheep”, which goes back to John, not Revelation, it is obvious Jesus was referring to Gentiles.
In the end, who the symbolic 144000 are aren’t a big deal. Much of Revelation seems to have been about events that occurred in the first century. And it was a controversial book that almost was excluded from the Bible canon. But it was finally accepted into the canon by Trinitarians in the 3rd century.
2. I can find lots of information as to scriptures that show how God and Jesus can be the same. But if Jesus is God, how did he send himself to earth ? And how did he pray to God when on earth ?
The Trinitarian theology is that the Father, Son, and Holy Spirit are three distinct persons, but share the same divine essence. Three Persons in one God, all equally divine, but having different roles and relationships to each other. Thus in this view, Jesus doesn’t send himself to earth, the Father does. Jesus (one person) prayed to the Father (another person).
Of course, in mainstream denominations, people don’t really sweat this stuff and it is no big deal. People end up having personal views on these matters and don’t spend much time thinking about it.
3. If God and
Jesus are the same do other religions still ask their prayer in Jesus's name or
do they just say Amen ?
Yes, many denominations pray in Jesus name. Again, they pray to the Father (one person), in Jesus name (another person). Or as directed in John 14:14, they can pray to Jesus (“ask me anything in my name and I will do it”).