Open Access from VB.Net

Using some code from the Microsoft website, I can now open the database, and view the form.
http://msdn.microsoft.com/en-us/library/aa167790(office.11).aspx
My modified code is below.
However, I still have some questions:

1) If the database is already open, I'd like to switch to it and open the Clients form there. How can I set oAccess to the open database?
2) Some of my users have the runtime version of Access instead. How do I use that instead?
3) I want the Access window to be maximised, but oAccess.DoCmd.Maximize() doesn't work.

Thanks!

Dim oAccess As Access.Application
Dim oForm As Access.Form
Dim stCriteria As String
Dim sDBPath As String
Dim sForm As String 'name of form to show
 
' Start a new instance of Access for automation:
oAccess = New Access.ApplicationClass()
 
' Make sure Access is visible:
If Not oAccess.Visible Then oAccess.Visible = True
 
sDBPath = DB_PATH
oAccess.OpenCurrentDatabase(filepath:=sDBPath, Exclusive:=False)
oAccess.DoCmd.Maximize()
 
' Now open the form for specified Client
sForm = "frmClientMain"
stCriteria = "Branch = " & iBranch & " AND ClientID = '" & stClientID & "'"
oAccess.DoCmd.OpenForm(sForm, Access.AcFormView.acNormal, , stCriteria)
 
' Release Application object and allow Access to be closed by user:
If Not oAccess.UserControl Then oAccess.UserControl = True
System.Runtime.InteropServices.Marshal.ReleaseComObject(oAccess)
oAccess = Nothing

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