How best to integrate LR with Google Photos?

That is exactly what I mean indeed. if just having the adjusted copies is fine than it is probably a good solution for you indeed. I need my original raw images backed up and it won't do that so for me it doesn't work.

Zak, this would put jpeg copies with all changes baked in on your google photos. The image size will depend on your settings in the plugin. They can be full size to whatever reduced size you want. Google has no clue about any of the develop instructions or metadata that Lightroom uses so this is the only option that gives you fully developed images. It is NOT a backup solution therefore, just a way to have images somewhere. They can be a good last resort if you lose all your images in some catastrophe where you would still have all your pictures somewhere for posterity (At least until Google decides to can google photos - they have a habit of canning services that they no longer feel is making them money) If you actually want to backup your original images and Lightroom catalog somewhere offsite, you need to do something like amazon storage, google drive, Dropbox, or an automated backup software solution. Such solutions work well but are limited by your internet upload bandwidth and if you're in north America, that is usually really slow And Lightroom catalogs including images easily grow to many 100's of gigabytes. I have several terabytes of images for example. Also be wary of data limitations that are becoming the norm in the US too. This is why external hard disks are so convenient for backup as they are orders of magnitude faster. They have the disadvantage of being in the same house though and so get lost too if your main computer gets lost due to fire/water damage. You can always make a regular backup to a hard disk and store it offsite in a safe deposit box If you want to be sure. Some of the online backup solutions allow you to make the first backup by mailing them a hard disk Which might be a good solution.

I have used the Jeffrey Friedl Lightroom to Picasaweb plugin for several years, but it no longer works. I now have to publish to Google Drive using Jeffrey's plugin, and, and then manually copy the photos into the relevant Google Photos Album. It is really a bad backward step and very clunky. I'd love a better solution as Google Photos is my preferred method of sharing photos with others.

There is an option in the Lightroom Catalog settings that you can choose that says, "Automatically write changes to XMP files". This will write many of your changes (but not all) to XMP files for your raw images and will write the changes to other file types as well. I have never done this. It is my understanding that doing so can affect the performance of Lightroom. Someone else may have a different view of this option.

You need to understand that the only file Lightroom opens is the catalog. The catalog is a database that is populated with image objects to show your images. It is essential that you backup that catalog on a regular basis. Look through your menu options and find the catalog settings and you can choose how often you want to backup your catalog. That backup DOES NOT back up your images. I suggest that you create some sort of plan for backing up your images. That does not involve Lightroom in any way. You can get software that will automate the backup process. Or you can have Lightroom created a second copy of your images as it imports them. Those backups should be on a different hard drive from where your working images are located.