Hi Tommy, I have the same basic setup as you, but have added an ES ED80 CF to my collection.
Here are a few things I have learned that may be of help.
First, the AR 102 does work ok for visual observation on the iExos 100, but it can be a little “jiggly” if you have to touch it (change eyepieces, etc.) The mount can find and track a target ok for visual use. Yes the better the PA the better your results. I have a Rigel Quickfinder for a finder scope, and for visual targets, it works great. Another item I have found very helpful is the 1.25" Wireless Illuminated Reticle Eyepiece with Focusable Dual Crosshair - 20mm. I don’t know what eyepiece you use initially to center the target for your alignment, but something with a large wide FOV to start works great. Another option would be a 26mm 2 inch eyepiece. I have found that its not unusual to have to slew the mount a little to center the target with ExploreStars to complete the alignment. You don’t mention what brand of ExploreStars your using. I have both iPad and Fire HD8. I use the Fire most of the time.
Regarding astro photography, (and I consider myself a beginner), I got the ED 80. Its much lighter, and the shorter focal length (480 vs 663) makes it easier to find targets. I do use a .8x focal reducer as well. You could use a focal reducer with the 102, but it would add a little weight and extend the length. I use the AR 102 for visual use, and the ED 80 for visual and astro photography. Regarding oblong stars I have found 45 secs the max and 30 secs works best. I don’t use a laptop, so mine are all unguided. I do use my DSLR and a few lenses a lot with my iExos 100, and have had great success (I think). Taro Seki is a member of this forum and has posted outstanding photos on his website Astropical.uk. His are unguided and usually 30 secs. Hope this helps.
Vero Beach, FL
Scopes: ES ED80CF, ES AR102, Meade ETX 90 EC (Deforked)
Mounts: ES iExos 100-PMC Eight, ExploreStars IPAD & Fire HD8, Explore FirstLight EXOS Nano
Nikon D600, D5500