Should I pick inline styles or a separate CSS block?
A separate CSS block for anything on a web page: it is smaller, and you can restyle the whole table from one rule. Inline styles only for HTML email, where many clients strip <style> elements, so declarations have to sit on each cell. Inline output repeats the same padding and border on every cell, so it grows fast.
Is this table accessible?
Partly. Keeping the header row on gives you real <th> cells, which is the single most important thing. It does not add scope="col" or a <caption>, both of which help screen readers. Add them by hand: a caption naming the table and scope="col" on each th.
Can I put a link or an image inside a cell?
Not from the tool. Cell content is HTML-escaped, so <a href="..."> comes out as visible text rather than a link. Generate the table structure here, then paste the markup into your editor and replace the cell text with real markup.
How do I make the table scroll on mobile instead of breaking the layout?
Wrap the copied <table> in a div with overflow-x: auto. The generated table is width: 100%, which on a narrow screen squeezes columns until the text wraps to one character per line. A horizontally scrolling wrapper is almost always the better answer for a data table.
Why is my first data row striped instead of the second?
The generated markup has no explicit <tbody>, so the browser creates one containing every row, including the header. nth-child(even) then counts the header row as the first child. It looks right in most cases, but if the striping is off by one for you, adding a real <thead> around the header row fixes the count.
Can I resize the grid without losing what I typed?
Yes. Changing rows or columns keeps existing cell contents in place and only fills the new cells with blanks. Shrinking the grid discards the cells outside the new bounds, so widen before you narrow.