... Why aren't people doing something to protect their homes?
In reality, there is nothing they can do.
... Would spraying the house with fire retardants or foams save them?
No. The lava presses right up against the house structure, igniting it. It would have little difficulty pressing right past a barrier. Also, it's intense heat alone has caused fire to start before the lava actually touched the structure. Fire aside, the lava is essentially an unyielding force. Even without burning the structure, the weight and force of the lava field could destroy it or cover it.
... Why don't people bulldozer a dike or moat around their homes to channel the lava around them?
It's been tried but it doesn't work in the long run. A dike would need to be solid enough and high enough plus be built at a 45° angle to the flow. That's just about impossible. Making it solid enough would require lots of material which is not readily available. Plus it would takes days of bulldoze work to construct and compact such a dike. Plus, you don't know in advance from what angle the lava will be approaching your property, so getting the 45° angle would just be sheer luck. The chance of it being made high enough is practically nil.
Building a moat has its own challenges. Most areas have solid, though fractured, lava under the top layer of ground. It's our own substitute for bedrock. So a bulldozer can only scrape away so much before it hits solid lava. Thus only a shallow moat could be bulldozed in most cases.
Lava does not flow like water. While it generally flows downhill, it is capable of actually climbing uphill. This happens because of the way the surface of lava cools and solidifies, plus fresh lava pushing on from behind. The fresh lava often moves and lifts the cooled crust, thus causing the lava front to rise dramatically in elevation and "climb" obstacles. On top of that, while some lava flows may only be a couple feet thick, others can easily be 20' thick! So you'd have to have an incredibly high dike or deep moat for it to have any hope of being effective. In experiments that the government here has done in the past, lava flows easily crossed fairly high dikes, especially those built perpendicular to the flow.
... Why aren't people evacuating the area?
Most people close to the eruption have indeed evacuated. Some have chosen to stay because they fear losing everything to looters. Historically, Hawaii officials have done an abysmal job when it comes to controlling looting. Homeowners have returned to empty houses where even the sinks, toilets, and copper pipes were taken! Even with this eruption situation, where supposedly the police and National Guard are protecting the area, looters have been ransacking some of the houses where there are no neighbor's keeping guard. A couple of them have been arrested, but most are evading the police.
... What happens when the lava cuts off the escape road?
Simple -- people and animals get trapped. Some people will chose to ride it out until the lava gets real close rather than safely evacuating. There have already been cases where people have called for evacuation. In some cases, people can walk out via routes that cars cannot get across. In other cases, the Marines are on standby to conduct heliocopter evacuations, but lack of landing sites plus ashy smoke might interfere. I am guessing that small animals may be evacuated along with their owners, but that will not be possible for large animals who will have to be left behind to a horrifying fate.
... How long will this go on?
Nobody knows. It could last a few more days, weeks, months. Or years. Pu'u O'o erupted lava for 25 years, with just a few breaks in the action here and there. This could become the new replacement for Pu'u O'o.
... Why don't they just bulldoze the lava away?
First of all, the lava is too hot to get near. It's over 2000°. I've personally been within 10 feet of a shallow, small pahoehoe flow.....very small slow flow.....and it was bearable only for less than a half a minute. All the hair got singed in my arms and legs even with that very brief exposure.
This lava that's erupting is hotter than what I experienced. Plus it is a far greater volume. My lava flow was about a foot or two in height. The lava in Puna is many, many feet thick. The sheer volume of molten rock is staggering.
A bulldozer could not possibly push molten lava aside. The metal of the dozer would become red hot, plus the paint, hydraulic fluid, lubricants, and fuel would burn along with any non-metal parts. The operator would be overcome by the fumes and heat. So there is zero chance of bulldozing flowing lava.
... Why don't they dynamite the front of a lava flow to stop it?
It won't help. In the past they tried dropping bombs in a flow to stop it or change its route. Didn't work.
... Why don't they pump ocean water onto the flow like they did in Iceland?
First of all, it's not close enough to the ocean. Secondly, the coastline is too dangerousness to bring a firefighting boat in close enough to shoot water inland. Third, the lava field is immense. There is more than one flowing front. It would take a fleet of boats, which are not available. Plus the lava fields are mostly inland. Four, the fumes coming off the lava eruption could overcome those on the boats, depending upon how the wind shifts. Right now it's blowing right out to the coast. Five, there's nothing in the lava's path along the coastline that is valuable enough to justify the expense and jeopardize the lives of those on the boats. And six, it won't do anything to stop more lava from coming out of the ground.
...Wouldn't the a good rainstorm stop the lava?
Simple answer, no. Raining on this lava is like spitting into the ocean. It won't make a bit of difference. Rain just results in more steam driven clouds of noxious gas. The lava is erupting out of the ground from the massive pressure behind it. Cooling the surface with a bit of rain (or ocean water) won't do anything to combat the incredible underground pressure that's driving the flows.