maybe they can check out the checks before they clear to see if the account they were written on is still valid and there is enough in the account to cover it.

Depending on the bank, they usually charge a fee for bounced checks. Ours does $15 per check that was bounced and then they take the amount of the check out of our account if they had credited us the amount of the check. It is a processing fee.

I don't loan money out anymore because most of my friends I loaned money to never paid me back. Some of them did, and at least made small payments per month until paid off. But I am not in a finacial position to lend money out any more.

Some checks have an expiration date on them, like no longer good 30 days after the check was written. If not, I am told the bank will take checks up to 6 months old if they are not marked when they expire. In special cases they might take a check over 6 months old, but I am not sure what the conditions would be.