There are two types used, The orange ones with the 350 part number which can be used on the B and BA are filled with nitrogen and have a steel bottle. The 355 number items are grey in colour, use helium as the gas and have a composite bottle. The 355 floats are a lot bigger for the larger AS350's and are a real pain to repack compared to the orange ones. If you are thinking of repacking the float yourself to get out of trouble ( if that's what you are thinking ) and saying later "how did the bottles loose all pressure so suddenly?", think again as it easy to spot a bag that has been feild packed and both bottles are fired using an explosive squib. So no you won't be able to refill them yourself and either will your local gas guy and Eurocopter won't send DG Squibs out lightly either.
I have seen only one uncommanded float fire, the helicopter was operating low level along the coast and only one went off, all others have been pressing the wrong button cases.
The only checks you do are the continuity checks and bottle pressure checks, it will get pretty expensive if you want to fire them off for a functional check.