Starting a 20gal

[skabooya]

I am so confused. I just got a response on another reef forum and this person basically told me i need to rethink my entire plan.
Do i have to have a 4" deep sand bed?
Do i need to have 2 powerheads? I thought i K1 would be enough since flow is dispersed everywhere.
Is the rio that bad where i shouldnt bother at all? I thought something was better than nothing. I cant in any way afford a remora.
A bucket of salt will last me more than a year. Is this true?
Is instant ocean really that crappy? Its all my lfs supplies. Aparently it has low alk buffering capacity is that true. That worries me because i have very soft neutral to acidic water out of my tap. (The tap water he is amazing lots of people do salt where i live and use tap)

Please help me out. Im getting discouraged again.