1. Yes but it will take some math and at least one more element. At the bottom of the form there are two elements which you can not see. A Calendar Month and a Calendar Year. If you combine them both into another element you have a unique Id which you can use for the XPost.
Now comes the Tricky part. The boxes(Elements) on the form are named D1 through D42. D1 being the very first box and D42 being the last. D1 is not always going to be the first of the month. The code for figuring out which D Box is going to hold the first days information can be found on the Next Record Button, The Prev Record button, or the Form on Form Entry event.
2. At the same time as the XPost, Simply just post a string variable
Var vStuffToPost as String
vStuffToPost = "~" + ValueToBePosted
XPost("Data\Calendar.db", "5_1995", "Cal_Key", vStuffToPost, "D26", "ADD")
3. Are you talking about multiple people using the same form or have a different form for each person(Sally_Calendar, Joe_Calendar,..)?
-Ray