Add me to zoom camp. It is an option for iOS devices last time I used an iOS device to take photos with the app and I was disappointed it's not an option for Android devices. I was in a mausoleum last year and I couldn't get the app to work before I went in the mausoleum so I took a bunch of photos using the Android's camera and zoom came in handy as some of the vaults were 6 high. Without zoom, I won't be able to get those above maybe 3, possibly 4 high. This mausoleum is one of several in the area that are hard to get into. It's only unlocked twice a year, Memorial Day and Christmas Day.
I haven't tried preview mode in a while, but it had a bad habit of showing a photo that appeared to be in or out of focus, but once uploaded, some of the photos were actually the opposite. I ignore how the photo appears in preview mode now except to use it as a gauge if the photo successfully took. In a small percentage of photos, the app seems to take the photo, but when I go to upload and look for the photo, it's not there. With preview mode, if the image doesn't show up, it means the photo wasn't taken so I know I need to retake it. Be great if I could rely on it to know if the photo was/wasn't blurry.
In terms of the auto-focus, I usually turn it off because it was having too many problems. I haven't photographed lately due to winter, but I am hopefully auto-focus has improved as I find it helpful when it did work.