A few Surface details, maximums, and wireless tidbits.
All Surfaces are Dual Band 2x2 meaning they have two antennas and support two streams on either 2.4 or 5ghz bands which will determine the maximum connect speed. The connect speed is not fixed but varies due to conditions at the moment. The Surface RT, Surface Pro, Surface 2, and Surface Pro 2 have 802.11 a/b/g/n wireless capability and their maximum connect speed is 300Mbps. The Surface Pro 3 has wireless 802.11 ac capability (a/b/g/n/ac), it's maximum connect Speed is 867/866.5 Mbps and it will also support a/b/g/n wireless communications as well.
Imagine wireless as the waves on a wind blown lake, the walls and objects reflect and disrupt the waves which can reduce the max signal strength but also bounce around corners. Direct line of sight provides the best connectivity although signals can also travel through walls and reflect off walls to adjacent rooms. Your lake is looking a little choppy now. Beam forming technology attempts to manipulate the waves so that a wave peak occurs at your device giving you the maximum signal.
The maximum throughput or transfer rate will be something less than the current connect speed due to overhead and various other factors. Multiple clients/devices connecting to the same router compete or share the available bandwidth so transfer rates may be further reduced if multiple devices are communicating at the same time. On the 2.4 ghz band which is also used by portable phones, baby monitors etc. interference can impact performance as well. Densely packed neighborhoods can have many routers and other devices jockeying for position and congesting traffic like a busy road. The 5ghz band has less congestion from other devices currently although that could change with the Internet of Things and many many devices getting into the act.
Your Router should exceed your Internet and client capabilities so that it can handle multiple devices and dynamically adjust for suboptimal conditions or interference from competing or neighboring devices and still be able to deliver the maximum Internet speed you have subscribed for.
Future technology, wiGig or 802.11ad will introduce another frequency band, 60 ghz for devices to communicate on. This frequency does not travel through walls but is capable of much faster communications within a confined area. Initial speeds will be up to 7Gbps and with 4x4 MIMO could go up to 28 Gbps. This will make it possible to use wireless docking, storage, networking, displays and other devices simultaneously while localizing traffic and offloading the longer range AC and N communications on 2.4 and 5ghz bands.
Best of luck with your wireless adventures.