I noticed that in wiki page, somewhere, it has been mentioned that with wifi module we need core+ and not core module to program. i found it after lot of digging. a suggestion would be to kindly put this somewhere on top and highlight this difference. so that one who is buying individual modules can choose correct one and avoid mismatching.
finally, i have managed to upload sketches from arduino IDE with wifi ESP module and core module together. i just had to link tx and rx pins externally with wires. ( i did not try soldering because i do not have pointed good quality solder tip).