In CSS, the "margin" property is shorthand to allow all four margins to be defined in one declaration. One starts at the top, then goes clockwise. So...
...defines a 1em margin at top, 2em for right, 3em for bottom, and 4em for left. There's also shorthands for the shorthand. If you give only 1 number, then that's applied to all four margins. If 2, it'll take the first as top and bottom and the second as left and right. Full reference at:
https://www.w3schools.com/css/css_margin.asp
Regarding precedence... in CSS, this is called
specificity (more at
https://www.w3schools.com/css/css_specificity.asp). There are actually a lot of rules about this, and to be honest, I used to always struggle with this myself and my CSS would look like graffiti in a bathroom 'cause I'd keep experimenting with things till I got the output I wanted, but not being quite sure why things didn't work before.
My strong advice is to bite the bullet one weekend and read a couple of introductory chapters about CSS. The topics you want to know well are
specificity and
selectors. You don't need to know much about various properties - you can learn those as you go - but understanding specificity and how selectors work, including more complex selectors that define parent/child relationships (e.g. applying a style to lists that are inside table cells only) will be an investment of your time that will continue to pay dividends later on. Also, there are just some things you cannot do in the Flare GUI that I find indispensable (e.g. Assigning multiple classes to an element).
To get you started, if you want the margins for a list style to be different inside a table cell without changing how that style looks elsewhere, you can use the following selector:
The angled bracket says "for all unordered lists that are an immediate child of table data cells", apply a left margin of 1em.
Another thing to look out for is whether your text in the <li> item is wrapped in a <p> tag. You'll likely get different formatting with and without the <p> if you've done what I've done with line spacing.
Curious about the padding being ignored... I'm wondering if there's a negative margin somewhere? Or check the code.. I know when I enter text and delete it inside a table cell, have to reapply the cell style to get it back to what I initially had (in the XML editor, select table cells, right-click, select Cell Content Style, then reapply the cell content style you defined).
Good luck!