You need the std Shimano outer cable, it just fits on the ends and the plastic tube fits between the supplied fittings in the kit.

You still need the outers, this just goes over the exposed inner to make them waterproof

No. This covers only the exposed parts of cable so that no bare cable is exposed to water, mud, etc. The included ferrules have a nipple that neatly slides into the waterproof sleeving & everything fits perfectly so it looks good too!

you need both, this only covers the inners, very simple to use

You will need to get some cable outer. If you run outer cable the full length from shifter to deraileur you will not need this waterproof kit...but if your outer cable runs in a few pieces between braze-ons on your frame this is ideal to seal exposed areas of inner cable. I use a Sram Attack shifter and the inner cable that comes with them with shimano xt sp41 outer cable. Shimano xt sp41 outer is really cheap and works well. This kit comes with the ends you need and liner tube to cover exposed areas of your inner cable and fits nicely with the xt outer. Its a doddle to fit. You may need cable cutters for the xt outer but you can use a dremmel or similar tool with a mini cutting wheel which cuts nice clean ends very easily.

This just fills the spaces where bare wire shows, so can continue using the same outer as you currently use (unless of course that needs replacing). The pack comes with all that you will need. The other option to this is getting a new length of outer that will go from your shifters to the last cable stop nearest your rear mech. This creates a water proof setup but you would need to zip tie the outer to your frame instead of using the cable stops. Works out cheaper as well probably and then you really do have a fit and forget gear system.

These items replace the end caps on each section of outer and the tubing gets cut to length so that it overlaps the new outer cable ends and covers the exposed sections of gear cable. This basically reduces the entry points for grit and water down to your shifters and the end of the cable run near your front or rear derailleur.

theses are not cables they only cover the cables to keep out dirt.

I think this kit will work with most types of shifters..but it is only a waterproofing kit to cover exposed areas of inner cable between braze-ons on the frame. You will still need an inner cable and outer cable. I have used Shimano xt sp41 outer cable for the last 12 years without any problems and whichever inner cable comes with the shifter. The waterproof kit works well with xt sp41 outer and is a cheap and worthwhile upgrade.