I understand your frustration, and believe me ive been there too. The problem is too many people want to give their opinion saying what they say is the way you should do it. Forums many times dont help much, because you dont know if the person giving you advice knows what they are preaching or know how to keep good tank husbandry at all.
Unfortunately, in this hobby, there is no guarantee and my advice is to read as much as you can on the internet from articles and credible sources about proper tank care. Books are outdated and have limited info, when you can get in your computer and search for everything you want. I have a couple of products I use that I learned by trial, and now trust. Of course, during my "trials" I made mistakes and learned from them. Listening from LFS
's is in my opinion the worst thing, because many times(amazingly) they seem to give you bad information or try to push you something they have to sell. If I go today to 5 different stores around my house and ask about the best salt, I will probably get 3 different answers. Instant Ocean is a great brand, used by many, and maybe is not the best, but shouldn't be far from it. In any case, you could use it following its recommendations and have no issues keeping fish or corals. As far as filters, it depends on what size tank. I opted to get a sump, and I think it is the best thing you can do. Your tank will thank you for it. It allows larger volume of water, keeping a more stable system, allows you to hide some of the equipment, and giving you the room to upgrade your accessories to things you might consider in the future, such as extra filtration, protein skimmers...
For the cycling problem, I believe your live rock having come wrapped in paper and plastic would have kept lots of the bacteria and will speed up the cycle. I would add a small inexpensive fish and let it do the cycling...I dont like to throw food in the tank because you never know how much is right for the cycling to properly take place.
Don't feel discouraged, soon you will be happy with your tank telling about a good experience