In a 3 fl hs, should get a wi-fi extender, booster, Repeater? My internet connection(150 MB) 1st floor Router&Wireless are faster pls in.?

150 MB - you probably mean 150 Mbps. 150 MBps is equal to 1200 Mbps, which I suspect is not the speed of your ISP connection.

By first floor do you mean the bottom or the middle floor? Having the router on the middle floor will normally give better coverage.

Personally, I would consider installing a wireless access point on the two floors that do not have the router, and running Ethernet cables back to the router. You could have the router and the WAPs all using the same SSID (network name). In this case they would each have to have the same pass phrase as well. The other alternative is to use different SSIDs, which is the option I normally choose.

WiFi extenders that us WiFi to connect to the router and to devices typically reduce the bandwidth by around 50%.

I hope this helps.

If the house is that large I'd actually go with one of the newer mesh routers. These come in packs of 2 or 3, but you can add additional units as well.