Hi oren1s and welcome to C.P.F.
Thank you for joining us. It's a nice place to hang out and there are many knowledgable and helpful folks on this site.
#1, If they've never been used, and are in mint condition, no leaks, all parts accounted for, hopefully with the instructions (if not, then perhaps a web search might provide them from the manufacturers website) you will probably be OK using them, however, READ AND HEED ALL OF THE MANUFACTURERS INSTRUCTIONS AND CAUTIONS.
Do not use them in confined areas with no ventilation. Any burning fuel produces carbon monoxide which is is lethal. A carbon monoxide detector and a smoke detector are strongly recommended.
There are some additives that may be added to the Kerosene to help it last longer, reduce smoke and soot, and some of them also reduce the odor as well.
#2. DO NOT
REPEAT DO NOT
USE GASOLINE AND/OR RELATED LIQUIDS IN A HEATER MADE FOR KEROSENE. THIS IS A DEADLY COMBINATION!!
#3. No matter what the heat source is, keep all flammable items well clear of the heat source, several feet at least. This includes, but is not limited to curtains / bedding / wall paper / and anything else that will not normally take this amount of neat.
Please make sure that you have a spill guard base of metal that will contain any un-noticed leaks from spreading on your floor.
#4. Do not fill it inside the building. Take it outside and let it cool off. Hate to spill some Kerosene on your floor and then light the heater. Yeoww! Wipe off any spillage and check for leaks before relighting.
Forgive me if I've covered material with which you're familiar. I've not personally used the units you describe, however they are most likely similar to many other brands that are currently available.
The information provided above is not particularily brand specific, and most of it is simply plain common "horse sense".
Please carefully research any information that pertains to your unit and heed the cautions.
It is quite likely that there are other C.P.F. members that have experience with this unit, and may be able to better address any concerns.
Let us know how things work out.
LH