Regarding the moisture getting between the gaps: Pre Finished Compressed and Non Compressed bamboo has been treated against moisture with the exception of the ends if cut, once cut they need to be sealed. Having said this It is suggested that when cleaning dont tip a bucket of water on the floor boards rather use a mix of water and metholated spirits with a small mop and lightly spread then wipe up with a static type surface cloth or towel. Similar cautions to normal timber.
Regards in expansion:
I only deal with Style Plantation Styleboard (TM) compressed and non compressed Vertical and Horizontal products. It is my experience that expansion happens width wise and not to much lenth wise, its very small. Personally I have not seen this affect any floors that we lay; and yes it does depend greatly on how its layed with respect to the Sika T53 or T55.
I dont know what you mean by "GAPS", I have never seen any gaps in our product. If you are referring to the beveled edges, they are only there to stop splintering; splintering occurs just like normal timber when something has been dropped on the join between two planks it may splinter, (I say may), or heavy traffic occurs with shoes such as stoletoes with sharp heals, the angle of the bevel also stops any issues such as expansion on sharp edges that leads to splintering.
Gaps may be occuring in some floors because they have not been tensioned when being layed, bamboo has the same tongue and groove joints as normal hardwood and also has them on the ends.
One way of making sure of the quality in my mind is to ask the supplier if their product is purchased in batches? and if each box is batch marked at the factory.
If you visit www.styleplantation.com you can download care and maintenance *.pdf files