Thats way too much perlite. I use 20-30%. Also perlite drys out faster than the soil, so it lowers the water retention. It should be ok for seedlings, you just have to water a little more often. It will be a pain in the ass to water when you transplant to bigger pots.

I would stay away from pre-fertilized soil, it makes it harder to tell how much food the plants are getting. You want to wait about 2 weeks before you start feeding.

Is that a liquid plant food? What are the NPK numbers on the back? You want one with higher N levels for vegging.