Hi @PhillipDunn,
In terms of asset storage current usage you can run Disk usage report - /etc/reports/diskusage.html?path=/content/dam
Manipulating value of path you can get different results. Above will calculate disk usage for entire dam, but if you more interested about specific folder you should just set path param to point to it.
Regarding available storage - I do not think this will be possible to get this information from AEM directly. You will rather need to check storage allocation for AEM instance itself on OS level.