Hi Dup,
Yes, you will see the shipping costs in the basket.
2-year warranty is on all eLicenser keys (from the date of purchase, so make sure you keep that receipt).
We see quite some keys from 2002 or 2003 (they have limited capacities), and if you treat your keys well (e.g., transport them in a padded bag, best close to your body) they will last very long.
How many keys, that´s really your decision. You can always stick with your existing system, if the initial startup time with the license check is something you can live with.
Best,
Paul