Yes, there is a relationship, and yes, there are tradeoffs. Higher frequency signals degrade over shorter distances, but can carry data more quickly. In the end, the thing you should be worried about however is which specification you choose to use; it has all the parameters built in. you just select a wireless-N router and wireless-N devices, and let it worry about the other factors.
Just because a spec uses a 5GHz carrier, does not necessarily mean that it will be faster. Wireless uses an analog media to carrier analog signals, so just like with wires, it is important for the specification to "square wave" (make approximations that are predictable and clearly defined) the different parameters of the connection in order to use it for digital transmission. So, once again, you are worried about the specification, not the underlying characteristics of the transport operations. For instance, even if 5GHz can theoretically carry data faster over short distances, a dual-band spec like N will carry the data at a constant rate, regardless of the band it is operating in. The spec rules all.
Environmentally, the only thing you need worry about are propagation and interference. if you have a lot of interference on the 2.4Ghz spectrum, then perhaps 5GHz is the right choice for you. If your walls a dense plaster or metal rather than light 2x4's and sheetrock, or you have power generation equipment nearby that interfers with wireless signals, then perhaps 2.4GHz is better.
hope that helps
