If you have that many topics and someone reads them all, they probably deserve to level up! 
tl3_requires_days_visited just needs to be 1 higher than tl3_time_period to disable it, e.g. it’s impossible to visit on 101 days over a 100 day period.
If you don’t want to allow images in posts, (and also don’t want to allow video, etc. either) you can increase min_trust_to_post_embedded_media to make it unavailable. For anything else you want new users to see, you can pin one topic as a global banner which will make the contents of the first post appear at the top of pages.
As an aside, it’s probably best to post new questions as new topics. It makes it easier for other people to find answers in future if topics have clear opening questions and a marked solution.