1. With TWS in DCS Russian planes you can have data (targets) on your MFD, so you can track targets moves, see it on MFD - In SCAN mode you don`t have data on MFD without AWACS or EWR data link or your lock. But iff some turn ECM ON in your radar scan zone your TWS not work, you will be in SCAN mode automated.
2. Sukhoi NO - MiG29S can engange two targets with TWS.
3. ECM not protect you against misliles but from enemy plane to have data about you like as Altitude, Speed, position... But keep in mind your ecm will be burned around 40-50km and they will have that data, so turn off ecm in that range because some missile maybe can find you on HOJ in that case.