ReadyNAS RN104 ESATA+USB

Does it support Hot swap on the ESATA, or must you add it then reboot the NAS?
Yes, it support
I don't have 2.5" seagate freeagent goflex ESATA, I need to buy one and check the issue.

-Once it is detected does it show up?
if the device is detect, system will auto mount eSATA/USB volume, then esternal driver will be shown up in UI(System/Overview page).

-Does it support Hot swap on the rear 2 USB3 ports or must you add it then reboot the NAS?
Yes, it support, but we don't test all USB3.0 device,
Coulld you tell me which USB3.0 driver do you use?
I used the below USB disk,
USB3.0 Flash
Kingston DT Ultimate 16GB
Corsair USB 3.0 16GB
Super Talent USB 3.0 16GB
Super Talent USB 3.0 8GB

USB 2.0 Disk 2.5"
WD USB2.0 500GB WDBABV5000ABK-00

USB3.0 Disk 2.5"
TOSHIBA USB3.0 500GB E05B050CAU3HS
TOSHIBA USB3.0 1TB E05B100PBUEAL
WD USB3.0 320GB WDBACY3200ABK-00
WD USB3.0 500GB WDBACY5000ABK-00
WD USB3.0 1TB WDBACX0010BBK-01
ADATA USB3.0 500GB ACH11-500GU3-CBK
Iomega USB3.0 1TB RPHD-UG3

USB 3.0 Disk 3.5"
Seatate USB3.0 2TB 9SEAN2-500 ===>Don't support.
ioSafe SoloPRO USB 3.0 1TB SJ1000GB
LaCie USB3.0 2TB Porsche design P9230
WD My boOK essential 3TB WDBACW0030HBK-01

USB3.0 Docking
Thermaltake BLAC X 5G
NexStar CX Super Speed
ORICO 8628SYS3-C (eSATA+USB3.0+Clone)

USB3.0 HUB
Syba USB3.0 4-Port HUB
Syba USB 3.0 4-Port HUB