Hi Jim:
I don't check back here in the PicasaStarter forum very often any more so sorry if you have been struggling for answers :-(
First, some definitions:
Picasa
Picasa is a program developed (or acquired) by Google that is installed on your PC and "manages" your photos on that PC. It has some photo editing features and methods of organizing your photos. Picasa manages the photos that are on your PC, it does not contain or copy or duplicate your photos, it simply shows them in their original folders and allows you to work on them.
Google has discontinued Picasa and no longer updates or maintains it, but it is still available on 3rd party websites.
A key feature of Picasa is that it creates and maintains a relational database with pointers to all of your photos along with key words, edits, album data, and face tag info. The database and search features allow you to instantly find photos based on any data fields including file name, date taken, any stored tags, albums included in and faces contained. This database resides in your Windows user data area (Normally on the C: drive).
Picasa Web Albums (PWA)
PWA was a Web based interface that provided a way to upload photos and albums from Picasa to your Google account so you could share them. PWA was discontinued by Google and was "replaced" with Google Photos. Google maintains that Google Photos is a replacement for PWA, but it is missing many key features of PWA.
PicasaStarter (PS) is a very special purpose utility that addresses some problems advanced users may have with Picasa, and tries to add some missing features. The majority of Picasa users have probably never heard of it and don't need it.
We (The Picasa TCs), maintain a FAQ about Picasa and Google Photos at:
Picasa and Google Photos FAQ The FAQ has a lot of info on installing and using Picasa and Google Photos.
Google Photos (GP):
GP is a Web based photo management tool. GP was conceived and developed for the Smart Phone crowd. With GP, when the phone user takes a photo, it is backed up & synced to your Google Photo account. This is touted as a backup function by Google, but is really more of a sync function since any changes or deletions to the photos on the phone are replicated in GP. This means if you delete the photo on the phone, it also is deleted on GP unless you take special care. Photos are arranged in one big pile by date taken.
Summary:
To summarize, Google Photos is a cloud based Photo management tool that operates on the web and stores your photos in your Google account on the Web. Picasa is a program you use on your PC to maintain the Photos on your PC. If your photos are in GP on the web, your only choice is GP unless you download your photos to the PC using GP. If your photos are on the PC, Picasa is a good option. Other options are Microsoft Photos or Lightroom, or one of several other photo programs.
You are not likely to need PicasaStarter unless you need to put the database somewhare special or needa portable or network version of the photos and database and are comfortable configuring windows settings.
Earl