Everything looks normal, keep doing what you've been doing. It is very important to be vigilant for pasty butt as it can kill quickly. As for their feed, it ultimately doesn't matter either way. While medicated can be mildly help with preventing coccidiosis, if they do get ill you still need to treat them with corridor. The most important thing to keep in mind with preventing coccidiosis is to keep the brooder clean and dry. Coccidiosis is usually only a problem when it's allowed to multiply out of hand and it thrives in a wet environment. Me personally I feed unmediated and bring the clumps of grass with the soil still attached so they can start building an immunity to the strains in my yard. My brooder stays dry and I clean once or twice a day (of course chicks being chicks they can create messes in no time) so it can't multiply too much and I haven't had any issues. The only time I would say medicated is maybe necessary is if you're in an area that where coccidiosis is a huge problem and/or has some particularly nasty strains. Also if you ever have chicks who are vaccinated for coccidiosis never feed medicated as it will make the vaccine ineffective