all these problems are electrical issues, you need professional electrician help.
leaking coolant is easy to fix,
trace the source of leaking by using dye method. water pump / hose flange & rusty housing may be issue.
all items including radiator & block welch plugs can be replaced.
swap is not recommended. 3sfe engine can be rebuild using oem new parts.
considering a swap is like trying to slaughter a humming bird with meat cleaver
- 2019 there was query for 3SFE FWD trany wth LSD thats what @hassan1991 referred to