It was intended that in the UK 4G (LTE) would use a different frequency to 3G and 2G, with the best being at about 800MHz where non digital TV used to sit. EE have upset the market some what by being given permission to roll it out at 1800MHz (used for 2G currently but EE have a ton of 2G spectrum already).
As far as better reception goes, that will depend on where the base stations are – probably on existing masts as it’s a ball ache to get planning to shove more up. That said it’s a basic rule of physics that says for a given signal strength a lower frequency will propogate better through ‘stuff’ (e.g. a house or building) than a high frequency. That means that 1800MHz 4G should be a bit better at indoors than 2600MHz 3G but not as good as 800MHz 4G.
All of this talk of replacing home broadband with 4G is basically tosh tho (at least in the short term) – that would require that the base stations have a lot of what is referred to as ‘backhaul’ (the connection from the base station into the ‘core’ network and then onto the internet proper). For places out in the sticks this is normally done via microwave dishes which in general don’t have a enough bandwidth to allow every tom dick and harry to sit on the net all day streaming dr who. This is why mobile data contracts still have data caps (even if they say they don’t) and why the data is sometimes traffic managed (e.g. bit torrent is given lower priority).
So whilst in theory you can use 4G LTE to provide broadband to rural areas (e.g. this is done in Aus and a bit in germany) it won’t be broadband in the normal sense of the word (i.e. like Virgin 30mbs service) as you’ll zip through the data allowance in 30 minutes if you get a quick connection.
On the other points, whilst the next iphone might support 4g in principal there is no guarentee that it’ll support UK 4g – the biggest market is the states and IIRC they’re operating at 700MHz for LTE. They’d need to add in a fancy multi band antenna and other bits of kit that will drain the battery and not be cheap – the market in the UK is non existant and even combined with aus and europe it’s probably still not compelling. You never know tho…
FYI 4G in Canada is normally what we would call 3G (HSPDA+ variant) which can actually go quite quick if set up correctly (like 24MBs in practice). Various telcos round the world argue that since this is as fast as some installs of proper 4g (i.e. LTE) that it’s not a marketing trick to sell it as 4G….
Edit: Apologies for the essay! Guess what I do!