Access to Excel Question

I have recorded and modified a macro to link an access database to excel. I have very little experience with VB and am having a few problems.

1: When I use the string filenm that is pulled from the worksheet for the file path I get the following error:
Data file: ‘C:\file.mdb’ not found. Would you like to connect to C:\file.mdb instead?
When the file name is hard coded I do not get this error, any way to get rid of this error?

2: How can I import only specific columns from the database table?

3: The data files I need to work with do not have an .mdb extension (they are db1, lf1, etc). The files are opened with access and when I replace the .db1 or other extensions with .mdb excel correctly imports all data. However, when left in the original .db1 form I get a window to “Enter MS JET OLE DB Initialization Information” and I can’t get the data to import. Can anyone help with accessing a database with out an .mdb extension?

Here is the code I'm using:

Range("B1").Select
filenm = ActiveCell.Value

With ActiveSheet.QueryTables.Add(Connection:=Array( _
"OLEDB;Provider=Microsoft.Jet.OLEDB.4.0; Password=""""; User ID=Admin;" _
, "Data Source=filenm;" _
, "Mode=Share Deny Write;" _
, "Extended Properties="""";" _
, "Jet OLEDB:System database="""";" _
, "Jet OLEDB:Registry Path="""";" _
, "Jet OLEDB:Database Password="""";" _
, "Jet OLEDB:Engine Type=5;" _
, "Jet OLEDB:Database Locking Mode=0;" _
, "Jet OLEDB:Global Partial Bulk Ops=2;" _
, "Jet OLEDB:Global Bulk Transactions=1;" _
, "Jet OLEDB:New Database Password="""";" _
, "Jet OLEDB:Create System Database=False;" _
, "Jet OLEDB:Encrypt Database=False;" _
, "Jet OLEDB:Don't Copy Locale on Compact=False;" _
, "Jet OLEDB:Compact Without Replica Repair=False;" _
, "Jet OLEDB:SFP=False"), Destination:=Range("A4"))
.CommandType = xlCmdTable
.CommandText = Array("BDBusVoltage")
.Name = "LL_M1_DCH_B1P_1"
.FieldNames = True
.RowNumbers = False
.FillAdjacentFormulas = False
.PreserveFormatting = True
.RefreshOnFileOpen = False
.BackgroundQuery = True
.RefreshStyle = xlInsertDeleteCells
.SavePassword = True
.SaveData = True
.AdjustColumnWidth = True
.RefreshPeriod = 0
.PreserveColumnInfo = True
.SourceDataFile = filenm
.Refresh BackgroundQuery:=False
End With

Thanks for any help.