Hi..
I would like to add FPV in my existing quad  and take live feeds on laptop .. any suggestion for the  Camera and Live feed TX &RX

There are many topics on the forum...plz do search! Anyways..
If you have a good budget go for GoPro or Mobius Action Cam(HD recordind+live feed)...5.8Ghz 200 mW with cloverleaf antenna and get HK's OSD...for feed to laptop i think you require a analog converter...(not sure about the name) or you could use screen(4.3''[No great with OSD..a larger screen required])  that comes with the Quanum DIY FPV glasses around 30$ from HK.
Regards,
Himadri.