The paving bricks are only thin, there may be concrete of simualar under the last few, but quite likely not, but you could replace them with edging stones like you have round the front.
The grass will look a diffrent shade intially, but it will come together over time. Unless the garden is very small I wouldnt re turf the lot, throw some weed and feed, followed by some grass seed, cover it with flease for a fortnight, and it will look a lot better without having the cost/hasle of new turf.
Daniel