it is called the ambulatory.
chevet
A Reredos.
Tiaria said its called the pulpit
It is called reredos. It usually has iconography or painting depicting an episode of bible.
The walkway between pews in a church is called an aisle. The wedding party and bride walk down the aisle to the front of the church. (The groom can enter from any door. He does not walk down the aisle in a formal procession, but waits at the altar for his bride.) However, other weddings not in church do not use a structural "aisle". They might place a "runner", often made of satin, across a lawn to create an "aisle" between chairs for seating.
An altar is actually called "the altar", although if there are many altars in a Church, they may be called by a specific name, like the main altar, the high altar, the side altar, the Blessed Virgin Mary altar, the altar of repose, the Blessed Sacrament altar, the St. Joseph altar, etc.
The bride walks down (or up) the central passage way not the Aisles (typically these flank the pews and are called the North and South Aisles)
in the tabernacle behind the altar.
Consecrated Hosts are stored in a locked Tabernacle, not on the altar. The Tabernacle may be located immediately behind the main altar or on its own pedestal in the Church, non on the altar.
Why didn't Prince William watch his bride walk down the aisle? Tradition. The groom is the last person to see the bride, and can only do so after she has completed the long walk down the aisle and is at his side. Since the aisle at Westminster Abbey is about 300-feet long, he had at least a four-minute wait at the altar.
Apse
An altar cloth.The altar cloth