Does replacing a damaged SIM slot changes the IMEI as well? I damaged my 3G (WCDMA) SIM slot which I need to get replaced/reparied.

I'm curious whether the replacement will also change the IMEI no or the slot? i.e. is IMEI info linkedup with the SIM SLot (Hardware) or is the information embedded in the phone's ROM
The SIM slot is independant from your antenna/radio so your IMEI will remain the same.
No need to worry about it at all.

The IMEI itself is usually inside your phone's internal read-only memory (On Samsung phones it seems to be inside the /efs folder).
Sidenote: Your IMEI + your IMSI are unique identifiers for your device. It's similar to a MAC address but works for cellular networks. Every IMEI can only connect once to every transmission tower, two devices with the same IMEI would cause both to lose connection.