Feeding can become a bit of a complex topic and I don't do it much, so I'll leave that for others to speak to.
As for additives, (even for a softie tank) you should maintain Ca, alk, and Mg. Supplement/maintain those, and do water changes. Most of the other additives you will see being sold are questionable to useless. If you buy a closet full of kent bottles (or any other similar brand), your probably making a major mistake
Some other additives may have some benifits, but if you can't test for it don't add it (one of many golden rules of reefkeeping). If you can't test for it, and your concerned, do water changes.
You'll likely get some conflicting advice other than the above (ie, I dose 20 drops of lugols iodine a day and it's really making my shrooms take off...). But take it slow, listen to LOTS of peoples experiences/advice, and find what works for you. In general though, most of the bottles on the LFS shelf are not necessary and possibly more trouble than they are worth.
Other words to the wise;
-If it says "marc weiss" on the label, it IS garbage
-If someone reccomends it saying something like, "this could be benificial", keep listening and ask way.
-If someone reccomends it saying something like, "you need to use this", keep listening ask why, then leave
-If one bottle says "boosts Ca, alk, and....." walk away. You can't put Ca and alk in one bottle in any usable form. (other than kalkwater mix, but that's another story)
-If it's too good to be true, well you know...
-bulkreefsupply.com is a great place to save a ton of $ and get the good stuff, in bulk, without the fancy labels. Look into their "two part kits" for your ca and alk needs.
