Speaking from experience ...
1) You should create a self-moderated thread in case of people who are spamming, it is easier for you to deal with.
2) go invest in a "copper" membership (
https://bitcointalk.org/index.php?action=credit;promote) so that you are able to post graphics. When I checked yesterday I saw it was around $15.00 USD.
Best wishes!
I would not recommend doing this. It's a huge red flag for everybody in the community if you're looking to self censor people. The moderators do a good job of enforcing the rules, so simply report any posts you think are breaking them. Deleting comments yourself, or even giving yourself the ability to do that, is a BIG anti-crypto policy and so that will reflect poorly on your service/business. As for your ANN thread appearance, maybe hire somebody for $40 or less to make a graphic for you?