The must haves are:
* An access point and access point client (many devices can act as either), along with a couple of directional antennas.
* You also need line of sight between the 2 sites (note that there should be a reasonable margin with line of site, ie you should be able to see above, below and both sides and have space to spare - look at fresnel clearance if you care for the specifics).
* Mounting equipment.
* An environment without too much wireless noise (easy to say, harder to do).
Ubiquity and Mikrotik are both good brands - ISP/Prosumer gear. I associate Microtik more closely with routers and Ubiquity more closely with Wifi devices - but this may be subjective. I've not used Mikrotic devices before, but I've been absolutely stoked with my Ubiquity AP - which far surpassed my expectations in terms of performance for a very low price.
You might or might not need a signal amplifier - but be careful with these as they can transmit past the limit - you are often better off with more expensive and more directional aerials.
A 1k line of site shot is easily doable (you could probably even use a "cantenna" if there is not much noise in your environment.
The lower the frequency the farther the signal will go, but the slower the speed/less channels.
The newer the standard the greater the range. An 802.11n device will perform 2-4 times as well as an 802.11g device, all else being equal. 802.11ac will give better throughput but probably not much more range.
if you don't already know, its important to understand that the more directional the aerials, the further the signal will travel but the harder they will be to line up. Highly directional aerials are also likely to pick up less noise (but this will depend on your environment).
The 5 gig band is a lot less crowded but does not go as far. If you are in a built up area its probably a better bet. In the country, 2.4 gig is great. If you don't have excellent line of site, lower frequencies are better.
