Hi Tommy,
For a general search, you could use Find (command-F, but don't click Find and replace). Enter your keyword into the find box, and Numbers will present a list of all cells containing the keyword:

Clicking on one of the list item will bring the table containing that occurrence, flash the search word, and select the cell.
For recovering a record (single row of data), using a specific search word, use a lookup or offset formula that treats the whole data table as a lookup table, looks for a keyword in the first column, then retrieves all or some of the cells in the row(s) where it finds that keyword.
Or you could use Categories to reorganize your table and to show only those rows/records that matched specific categories using the Reorganize pane.
Which method is best depends on how your table is structured, the specifics of what you want to extract, and how you want to display or otherwise use the results.
2
Numbers '09 does not support input forms, which is essentially what your "add window" would be.
I see two possible ways of simulating this, though:
Use a Main table with formulas to copy data from a smaller Entry table used for input.
This method would require repeated maintenance to:
- Replace the formulas in the data table cells used today with the data that's been copied to them (select > Copy > Paste Values),
- reset the formulas to begin copying the entry table into the next rows of the main table, then (with a leap of faith that all has been done correctly)
- delete the data in the entry table.
I can see opportunities for data loss to occur in that process.
Use an AppleScript to collect the entered data from the entry table, and place it into the Main table. This would icur the same 'location' issues as the method above, but for the most part, the dangers would need to be solved only when composing the script. Once that's completed, the data transfer and reset of the entry table would be a single menu item in the Scripts menu.
Which method to use depends on how your data is currently structured, and on the specifics of what you want to extract. Neither of the last two has been written yet, and it's possible that neither is actually workable.
Where to from here?
Regards,
Barry