About your questions:
1) Can't say much, but so far the lineart submitted on patreon is on page 23, I would estimate a count of 25 pages in total, and it's most likely that we will get this comic, either this week or the next one.
2) As for Konosuba #4, so far the sketch for page 11 has been submitted a few days ago, so at best the comic is coming at the end of August and worst at the beginning of September.
3) On my personal suggestion, work the best you can on the idea you have for that comic until you feel it's convincing enough for you, because there's the possibility of you getting a very good idea for the comic at the last second, that could potentially mess all of the progress made so far.
As for script writing, it's your idea so if anyone understands your own preferences the best, that's you, unless you want suggestions for that script of yours, but i think inspiration can be a great tool for your cause, just try not to be too perfectionist or very lazy, and you will be fine, just don't brainstorm too hard and rest if needed.
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