This issue was found in 0.9.0 and I think I have fixed this issue in 0.9.2. Are you sure you are using the latest version?
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Edit:
Fixed in v0.9.3

> Please add ability to enter time (hh:mm:ss) format and date too for single download

There is a "dateString" variable:
https://github.com/eight04/image-picka#filename-pattern

Does it fit your needs?

> this extension always maps back to downloads folder, instead must go to the folder I previously saved an image to just like built in firefox image download

This is a bug in Firefox. See https://github.com/eight04/image-picka/issues/15

You can't. In Firefox 57+, extensions can only save the files to default download folder. Also see https://github.com/eight04/image-picka/issues/14

Fixed in 0.7.1.

> the "Close tabs" checkbox closes the current tab even if you selected tabs to the right only.

Fixed in 0.7.1.

> Q1

No. It's a restriction of Quantum Firefox. Extensions can only download files to Firefox's download folder.

> Q2

See https://github.com/eight04/image-picka#filename-pattern

I would like to know in which situation you would like to change the base number?

How about to change the filename to `chapter1-${index}${ext}` and `chapter2-${index}${ext}`? So they don't overwrite each other and you'll know the chapter number by looking at the filename.

[Edit]
There is a new feature in 0.6.1. Now you can evaluate expressions in filename pattern. To use different base index, turn on the feature in advanced section, and change the pattern to e.g. "${index+20}${ext}" to make it start from 21.

Added in 0.6.0.

I'm not sure what do you mean "deleting same characters". If it's hard to explain it in a single review, feel free to open an issue on github: https://github.com/eight04/image-picka/issues

Recently used values are recorded in v0.5.0.

An "Ask me where to save the image" option is added in 0.3.2. You might want to remove the folder part in the filename pattern (Image Picka/${pageTitle}/)