Laterite/vermiculite mix

Dear folks, 
		After over a year of dreaming, planning, and building I 
am ready to fill a 50G (36" x 18" x 18") with water, some fish and lots 
of plants.  This is a show tank for the living room so doing it right is 
very important.  First off, in reading the instructions that came with 
the 500g of Duplarit G I am confused about what to do with the 10 
Duplaplant tablets.  Do I push them into the gravel? Dissolve them in the 
aquarium water itself or are they anti-anxiety pills that I shoud injest 
to calm myself?
	Secondly, After reading Jim Kelly's soil and  vermiculite  posts 
and more recently  his article in the last TAG on  soil characteristics, 
I am thinking of mixing the laterite I have with vermiculite.  My theory 
is that this mixture will have an increased cation exchange capacity than 
laterite alone.  What are peoples thoughts?  A discussion of pro's and  
con's would be appreciated.  
	Lastly, (for now) I've used Vallisneria Gigantea sp? with great 
success in a 30g 24"x24"x12" tank. I'd like some suggestion(s) for a Val 
tat tops out at the 16" to 22" range.

			Thanks for your time and advice,

						Miles Morrissey
						Easthampton, Ma
						mmorriss at sophia_smith.edu