Tackle for salmon
When fly-fishing any of the rivers there is no real requirement for huge double handed rods. Rods in the 13ft - 14ft range will cover most eventualities in the lower to middle river, although if yours is 15ft don't worry as it will still be very serviceable. At the top of the river a double hander can sometimes be more of a liability than an asset and a heavy reservoir rod in the order of 10ft is probably more suitable. In general floating lines with a variety of sink tips will cover most of the river but it would be worthwhile carrying a full sinking line as well (though not too fast).
Waders are necessary on most beats with chest waders being preferred by most anglers. From a health and safety a wading staff (ensure that the end is weighted and has a rubber stopper to minimise vibration), eye protection, and life jackets are recommended.
Flies are all about confidence and you should use what you feel comfortable with. Size is the most important matter when considering what pattern to use, with colour running at a close second. In general if the water is warm and lowish a smaller fly will be best and when the water is running a bit higher or colder consider larger flies. If there is a bit of stain in the water a pattern with a bit of brightness about it will probably out fish than a more sombre one. Popular patterns in the area at the moment are the Allies Shrimp (and all of its variants), Stoats Tails and various tubes such as Temple Dogs etc.