Create a field called, let's say "RecordNumber" and define it as an unstored calculation thus: "#" & " " & Get ( RecordNumber ) & " " & "of" & " " & Get ( FoundCount ) . This will give you a precise notion of where you are in the found set. As well, set up buttons like this: . The leftmost triggers the script step Show All records, then GoTo Record (first) etc. If you place these in the header of a layout based on the table occurrence that's appropriate it will work. The "Record Number" field is placed below, where it currently looks like "Record NU".
Regarding #1: you must make COPIES of menu sets/items before you can change them.
Regarding #s 2 & 3, I'm not clear on exactly what you're asking.
I hope the image of the buttons survives posting . . .
I can see the image didn't survive posting. So . . . the image consisted of four symbols with script steps attached. You can find the images easily . . . go to first record, go to previous record, next record and last record. The "Record Number" field is placed below the (grouped) set of symbols.
My guess on items 2 and 3 is that you want to modify the standard behavior of these two menu items.
To do that, write a script that does exactly what you want. You can temporarily test the script by selecting it from the scripts menu or assigning it to a layout button. Once you like how your script performs. You can modify a copy of the menu item to perform your script instead of Filemaker's built in function.