I'm trying to set up a routine where it sets the volume to 10, runs a routine and then sets the volume back to normal (5) after the routine is over. When I move the last volume 5 command down to after the routine it moves back up to the top and says this action cannot be the last action in the routine. Is there no way to set the volume, run the routine and then reset the volume?

You need to set up a voice profile and train Alexa to recognize your voice.

Here's a good writeup on how to do that on PC Magazine.
https://www.pcmag.com/how-to/train-amazons-alexa-to-recognize-your-voice

I used a couple of ihome isp6x for a few years, but stopped using them a while ago. I just dug them up and wanted to use them again.

The problem is that iHome sunsetted their control app and cloud service last year.

I can still use the plugs via Apple HomeKit. However, I don't have an Apple hub (HomePod or Apple TV) so there doesn't seem to be a way to automate the plugs.

When I try to set up the plugs in the Alexa app, it asks me to choose the plug brand, and when I choose iHome it wants me to add the plug to the iHome app--which is nonfunctional now.

Do I basically have to trash these plugs? I don't think there's any hardware out there that I can buy to use them that would be less expensive than buying new Echo-compatible plugs.

Exactly that.
Music is crisp with acceptable top end.
When asking  'Alexa, what is the weather' for example, it results in a muffled, over-bassy, low treble and low mid response in which altering the EQ does not change it whatsoever.

just for clarification, you are saying music is okay but not the spoken word?   

Working OK for me. Alexa simply replies "Setting a second timer..." "Third timer..." and so on. All timers are displayed on screen in a widget.