For my model, "HV301 26", I needed Torx T3 and Torx T4. You can buy them from iFixIt individually or as part of a kit, such as Mako Driver Kit - 64 Precision Bits.

For my model, "HV301 26", the hose recommended by Kevin Spink was exactly the same as the original hose: https://www.mcmaster.com/5136K11/ (thanks Kevin!). It has a reinforcing wire, so make sure you have something to cut a strong wire if you decide to use it.

The hose is reverse threaded: you must unscrew it clockwise on both ends.

There is glue holding the hose into the vacuum stick. I needed needle nose pliers to get a good grip in order to remove it. This destroyed the original hose.

The hose is about 6 inches total length, once it's unscrewed.

For my model, "HV301 26", there was no internal screw. The only thing I needed to do for this step was to unplug the cable.

For my model, "HV301 26", there were a total of 10 screws that had to be removed in order to remove the gray cover:
* The 5 screws mentioned in Step 1, which were Torx T4

* 2 more screws next to the big wheels, which were Torx T3

* 3 screws under the roller brush cover (Step 3), which were Torx T4

It's easier to remove the gray cover if you slip guitar picks (or these iFixit Opening Picks (Set of 6)) around the edges between the gray cover and the orange and clear bottom sections.

For my model, "HV301 26", I also had to remove the 3 additional screws under the roller brush cover (for a total of 10 screws when disassembly was complete). The 3 screws under the roller brush cover were Torx T4.

For my model, "HV301 26", removing the wheels was unnecessary.

For my model, "HV301 26", these 5 screws were Torx T4. I also had to remove the 2 screws next to the big wheels (right under the top two circled screws in the picture). Those 2 additional screws were Torx T3.

Additional notes:

* I originally tried using Flex Tape instead of replacing the hose. It was hard to wrap around the hose due to the awkward position of the tear, so it didn't stick well or last long.

* It's easier to remove the gray cover if you slip guitar picks (or these iFixit Opening Picks (Set of 6)) in the cracks between the gray cover and the orange and clear bottom sections.

* There is some glue holding the original hose inside the vacuum stick. I needed needle nose pliers to get a good enough grip on the hose to remove it.

* The hose needs to be twisted clockwise to remove it from the stick and from the dark gray end of the hose that attaches to the roller brush chamber

* When reinserting the dark gray end of the hose into the roller brush chamber, don't push it too far in. Otherwise, the orange roller brush cover will be blocked by the protruding dark gray end and won't close completely.

* The total length of the hose was about 6 inches

I have Shark "HV301 26", which has differences from the one in the steps:

* I needed Torx T3 and Torx T4 screwdrivers, instead of Phillips

* I had to remove a total of 10 screws: the 5 shown in Step 1, which were actually Torx T4 not Phillips #1; two more right next to the big wheels, which were Torx T3 (these were not circled in the picture in Step 1, but they're just below the top two that are circled in that picture); 3 more T4 screws that are under the plate covering the roller brush that's removed in Step 3

* I did not need to remove the small wheels (Step 1)

* There was no internal Phillips #2 screw as described in Step 5, so I didn't need to do anything for Step 5 except unplug the cable.

Note:

* I used the flexible hose recommended by Kevin Spink (thanks Kevin!): https://www.mcmaster.com/5136K11/ This is, as far as I can tell, exactly the same as the original hose, including a reinforcing wire inside the tube, and easily screws in. If you use this tube, make sure you have something to cut a strong wire.

When putting in the new battery, the battery ribbon cable did not line up with the dock on the motherboard, on the replacement battery I ordered from iFixIt. I was able to carefully peel back the foil covering ribbon cable, align the cable, then press the foil back in place. Now, everything seems to be working.