shade on the Ingles is no more than 40% of the way. But the first two days are walking by the coast, and therefore, the sea breeze should cool you down if it is hot. After that, you walk in the countryside in Galicia, which is always less going to be less hot than parts of the inland route of the Frances, because you are no more than 50km from the sea.
I would not say that you encounter people happy to see pilgrims on the Ingles. You don't encounter too many people at all, which is what makes the Ingles attractive. Because there are not too many pilgrims walking it, you have time for contemplation as you walk and peace when walking through the countryside. Where you stop and stay are normal towns (I would not describe them as cities), not towns set up for pilgrims. This though means you see genuine Spain.
Some of the guidebook stages do have limited accommodation at the end of stages, and some of the albergues are not large, but with some planning, accommodation should not be a problem. I do not think that you need to be up and out before dawn on the Ingles in order to secure a bed for the night.
As for trash, I did not see much at all on the Ingles. Because the route is not walked as much as the Frances, you are walking through normal countryside where people get on with their everyday lives. That means that bars and food stops can be 10km apart, but it does mean that you are walking through genuine, slow living, countryside.
Last point to add is that many guidebooks map out a 5 day walk on the Ingles with long 20km plus stages. You do not need to follow the guidebook stages, and if you take 7 or 8 days, for example; cutting the first stage from Ferrol to Pontedeume in half and staying at Xubia or Neda, and then cutting the Pontedeume to Betanzos stage in half and staying at Mino, you can have a much more enjoyable walk.
If you do walk the Ingles, think about flying into La Coruna, as this is often cheaper than flying into Santiago (you can easily take a train from Santiago back to La Coruna at the end of your camino), and think about spending a day in La Coruna exploring before you go off to Ferrol.
If you have never walked a Camino before, I would do the Ingles. As said above, it is 5 to 8 days, so if it turns out not to be your thing, you don't need to worry that you are stuck for 40 days or so. hopefully, what you will end up doing is loving the Camino experience, loving reaching Santiago, and then using the Ingles as some kind of taster for a longer Camino in the future.