Hello Agustin,
1) Yes, you can attach to the device.
In the debug configuration tick the option "Attach to Running Target"

2) This option allows you to preserve selected memory ranges - it basically dumps the memory range prior to the mass erase and programs it back after.
Default values and description might be misleading so we logged it as an usability issue.
The values/addresses entered are in hexadecimal format and value must be aligned to word size:
From: address must end with 0x0, 0x4, 0x8, 0xC.
To: address must end with 0x3, 0x7, 0xB, 0xF.
e.g. to preserve memory range: 0x1000 .. 0x1FFF:

Hope it helps.
Stan