A: No. The T311 has a different partition layout. Flashing T310 recovery on a T311 will likely brick the device or break mobile data. Look for t311 specific builds.
A: Also no. The LTE variant requires a different recovery image. t310twrp3101tarmd5 updated
A: Yes, if you backed up the EFS partition using TWRP. You can restore it via the Restore menu. Without a backup, your IMEI is likely lost permanently. your IMEI is likely lost permanently.