If I pick mail up, can I only retrieve it during normal business hours, or do I also get a key for after hours access?

I will see if I can retrieve the info for you.

Here's some data I retrieved regarding tax benefits Four ways that an LLC is taxed.

What sucks is your checkbook register balance gets out of agreement with the bank statement until they retrieve the check. 

Is there a more efficient way to get probate leads in Clark County other then going to the courthouse and retrieving three files per day as stated on the county website?

You could try the courthouse retrieval system.

I was able to retrieve the following information for about 25 properties before they closed: the Decedent, Personal Representative's name and address (sometimes phone numbers if available) and whether or not the deceased owned real property.

Their are several sites you can look up to retrieve the individuals phone number, current address, ect.

I'm not sure if it's even possible to retrieve these leads in my county.

I now use a Court Retrieval Software tool that gives me all the information I need.