We have one of these dispensers at our sink. There are several types of tubing generally used on these hot water units. The way these units work is that when you press the lever for hot water, cold water is sent to the heating tank which then pushes hot water up and out the spout. The supply to the lever valve assembly is high pressure cold water. Polyethylene tubing will work here. Generally the connections are push-in with internal o-ring seals. From the lever valve to the tank is cold water at lower pressure. Polyethylene tubing will work fine here as well. Also push-in connections are typical. From the tank to the spout is what appears to be a silicone tubing with some external clamps. This can handle the near-boiling temps and is typically not found available in most hardware or box stores. In fact, I've never seen it sold at retail. Polyethylene tubing is NOT recommended here at these high temps, but it may survive for a time because of the very low pressure. Splicing copper tubing into the middle of the silicone tubing would be an acceptable way to extend the length. You could possible extend the copper tubing on the faucet itself with copper tubing and a female-female compression connector. Another way to extend it would be to salvage some silicone tubing from an old drip coffee maker - due to the heat it is used to connect to the heating element and to carry the hot water up to the coffee basket.

IMO a tube does not have sides so I have no idea what you are asking. IMO I would get proper LED lighting not the tube type at all unless this is an office or some warehouse place.

We assume it's the ballast. That's why I always remove the ballasts. Otherwise, you're locked into the same routine of having to replace ballasts. The ballasts consume electricity & produce heat which partially defeats the purpose of switching to LED tubes. Ballasts fail sooner when they are installed in locations with frequent on/ off cycles, too. When you remove the ballasts, you need 'direct wire' LED's. Not the plug & play version. In the past (a couple of years ago), I found that there was little price difference between new direct wire tubes vs the cost of a new ballast. The technology for T8 tubes has advanced to the point where they are available in the traditional direct wire or the newer plug-and-play options. Plug-and-play T8 lamps operate with the fixture's existing fluorescent ballast, so no rewiring is necessary. The direct wire LED tubes run off of the line voltage that flows straight to the sockets. With this option the fixture's ballast must be bypassed and removed.

You need to revisit the pump. fountain pumps wear out and even if they are running and can push out water at zero head doesn't mean it is good. The impeller and and impeller shaft bushings will have an increase in tolerance due to degradation overtime and head pressure will be reduced. Most fountain pumps for your application are under $20 so unless the statue has an enlarged prostate the pump would be the only problem if the tube isn't constricted.