The Baha'i calendar contains nineteen months, each consisting of nineteen days, with four intercalary days immediately preceding the month of Fast. Although Baha'is consider every day to be for worship, monthly gatherings are held every nineteen days and are called Feasts. The three-part Feast opens with devotional readings, prayers, and often singing, followed by an administrative portion when community business is discussed/voted upon, and ends with socializing (usually around the pot-luck table).
There is no "main" or Sabbath day of worship in the Baha'i Faith. Every day is a day for worship. Every 19 days, however, local Baha'i communities gather for what is called "Feast" which comprises readings from the Holy Scriptures (not just the Baha'i Scriptures), followed by community business, and then socialization.
A Bahai place of worship is called: 1) a Bahai house of worship, 2) a Bahai temple or 3) a Mashriqu'l-adhkar These are three different names for the same thing.
There are Bahá'ís all over the world, in every country.
Yes, there are homes that belong to Baha'is in Wilmette, IL, as well as a Baha'i Home for the Aged. The Baha'i House of Worship in Wilmette is located at Linden and Sheridan. See http://www.bahai.us/bahai-temple
The Bahai community is very widely spread across the world, but in small numbers. Most local Bahai communities meet in private homes, or in a rented hall or a Bahai centre, and the same places are used for worship meetings and other meetings. However specially dedicated Houses of Worship / Temples / Mashriq'ul-Adhkars (3 names for the same thing) have been built in some places. There are continental Houses of Worship (for example, the North American one in Wilmette, Illinois) and two national ones are about to be built (Congo and Papua New Guinea). Local communities, especially in the third world, may have a small house of worship or Bahai centre built with local resources, and plans for a number of smaller Houses of Worship have recently been announced in Cambodia, India, Kenya, Colombia and Vanuatu. These will be built with help from the Bahais around the world, and will be in permanent materials.
Every day of the week is a day of worship to the Baha'i, as days are usually hemmed in prayer (morning, mid-day, and evening). There is no "special" day of the week, as Baha'is believe God deserves worship every day. There is no such thing in the Baha'i Faith as congregational prayer - it's a personal obligation - so there are no weekly gatherings for prayers to be led by a cleric of some sort.
A Bahá'í believer can worship, or pray, anywhere - at home for example. However, there are usually designated places in each town or city, where Bahá'ís meet to pray, to consult, etc.
Several Bahá'í houses of worship were built; so far, basically one for every continent (as of 2013, the one in South America isn't finished yet). You can find a summary in the Wikipedia article entitled "Bahá'í House of Worship".
Sunday is the day to worship God. You should really worship God all days of the week.
Worship in Judaism is every day, three times a day.
The Bahai Faith does not use any code in its scriptures, which everyone is encouraged to read for themselves. See the Bahai Reference Library for a good selection of Bahai scriptures, all for free. The Bahai community today also does not use codes, secret handshakes, etc..
Primarily, Christians worship in churches on Sundays.
They usually worship on Sundays.