The layout would import as long as the screen sequence or number doesn't already exist in the destination database. Whenever I did this it was on databases that were almost identical so I didn't have to worry about the tenders, slu's, etc. I don't think these table enforce foreign key constraints so the buttons will probably import even if they don't match, but who knows what, if anything, they'll be linked to.
This has to be done in dbidql. You'll have to write queries to get the info you need from both tables, then use the export feature to dump it into flat files. Import these into temporary tables in the destination database using dbisql's import feature, then you'll have to write queries to insert the data from the temp tables into the live tables.
Needless to say, if you're not comfortable with SQL you should play around on a test system for a while before trying somthing like this.