WN1000RP vs WN3000RP

The difference between the N150 & the N300 is probably the number of "streams" - wireless-n uses multiple "spatially separated" streams, up to I believe a maximum of four, it's theoretically possible that with two streams traversing slightly different paths you could see better coverage, but I wouldn't bet on it. The range issue is, so to speak, one affected by "the laws of physics" - the attenuation of the signal by distance and the materials used in the construction of your home - if you want to see an improvement there, find a way to reduce the distance - for example - relocate the router to a more central position - or - if you willing to spend the money, install a wireless access point, and cable it back to the router. The problem with wireless routers is that they are designed for convenience, so you have a router, a switch and a wireless access point, which ends up being located in a corner, convenient for the cable runs, but less than optimal for wireless coverage - the way around this is to use a wired router which can sit in the corner, with a wireless access point that can be optimally located - which is how I have done it - one single ¼" Ethernet cable runs to the access point, and provides both power (PoE) and data.