Make a simple DB
Make a simple import
Do a test
It all depends on what you actually want to achieve.
If you want to end up with just one table and delete the others then Importing them is a good solution.
If you want to keep the original tables and just see dates from multiple tables in one layout this can be done by adding fields from multiple tables to a new layout the main problem withthis approach is controlling which records are shown from each table but this can be done with buttons and scripts.
You could make a new table and use lookups from the other tables.
If you want to see which items are going to expire / renew in the next week month etc then I would build the relationship between the tables with what ever is appropriate as a match field. Then add portals to you new table which will show data from the other tables bassed upon the relationship.
Use a script to find the date range in each of the tables so that you only see the dates you are intrested in.
I hope this may point you in the right direction but without more details it is not possible to give any definate answers.