要和旧的完全一致吗? The answer is YES.

As you described, 1400 SQ FT.  You should have 3.0~ 3.5T.  The HAVC based on the sq FT.  You can search from Google.  However, you can choose one step down and never choose up.  Many people did not know why.  The main reason, higher power that make short run time.  In the summer, you need HAVC runs long time to exhust the hummity air.  If HAVC run short time that you save in electricity, your house will smell badly.

change coil is a easy job but motor.  You should have at least two more quotes then make decisions.  Good luck.