Would you mind expanding on your question a little more?  Did you have specific questions about these products?  Is there an issue that you are having, or are you just generally curious about these products? 

Thanks for clarifying.  Usually I wouldn't recommend putting anything in a hive unless you know that the bees needed it. There is no potion on the market yet that has been shown to be necessary for bee growth and development, and there is not a lot of peer-reviewed unbiased research on a lot of the products that support a lot of the claims that they make.  

I personally have not used Hive Alive, though I have used other products with lemon grass oil, including honey bee healthy. One thing that we do know about lemon grass oil is that it is an attractant.  When added to feed, it can cause the bees to eat more feed.   This can be useful if the bees are sick, or if you need them to take in a lot of feed.  It might be nice to add a tiny bit of one of these products to feed if you need a lot of drawn comb. 

Just keep in mind to have everything out before honey supers go on (and dont' extract from the brood nest), as you don't want it contaminating any honey.   

In my opinion, there isn't any supplement that is necessary for bees (just food!).  

Thanks for the solid input on this, very helpful.

Glad you found it useful!

Can you offer advise also on:

1) I use medium supers: should I use a queen excluder after the 2^nd or 3^rd super to allow sufficient space for brood?

There is no "should" in this situation, it is all preference, and it depends on what you want, and your bees.  In some places, they keep bees in smaller brood nests (single deep / 2 mediums), but the bees are selected to like smaller brood nests.  If you have bees that don't, or that collect a lot of pollen, they can clog up the brood nest completely. I would start with keeping 3 for your brood nest (put the excluder above the 3rd box).

However, if you are still trying to draw out wax, I would not use the excluder.  Bees do not like to go through an excluder when there is just foundation above it, and you will have a hard time getting the bees to go up there.  You can also just wait until your second year to put it on.  Plenty of beekeepers never use excluders, and just let the bees choose. While it is nice to use them to keep the comb nicer for the honey, it isn't essential for the health of the bees. 

2) Is there a good rule of thumb when to add more space in the form of a new super? At 80% drawn comb or at 80% capped comb of the uppermost super as example?

It depends on how fast they are filling it.  If it is a big colony and a fast honey flow, you should be putting supers on 2 -3 at a time.  If it is a small colony, you can put them on at a slower rate. Once the flow starts and they are drawing wax it is better to have too much space than to little. 

3) When is the honey flow the strongest here? This is what you will learn with experience and monitoring your hives. It really depends on what is in your particular area (with 3 miles of your hives), and the weather each year.