Unfortunately, of all the Stomatopods you could have gotten, you may have gotten the worst possible option. L. maculata needs a sandbed at least 1.5X it's own body length; best to plan by its fully grown adult length of 40cm (so a 60cm deep sandbed). if you can't accomodate that, sell/give it away to someone who can.
as for your other questions, most mantids cannot be kept together and you should NEVER mix species; so no you cannot have a smasher in the tank because you will invariably end up with one or both of them dead. L. maculata can form monogamous pairs and one pair in the wild has been under monitoring for about 15 years now! However, unless you initially buy a known mated pair, good luck in making your own. males are rare, females are almost never seen in the trade (because they stay safe in the burrow and the males do most of the hunting) and it is far from guaranteed that they will pair up even if you do manage to find a chick. L. maculata and any other spearing mantis does not need live food, so if you don't want to feed it live food, don't; never feed freshwater fish to a saltwater invertebrate imo. Mantids don't need a whole lot of food... I would feed yours a whole silverside maybe once every 3 days; if there are leftovers, clean them up and feed less next time. as with any aquarium inhabitant, it's largely trial and error.
read. this is from a stomatopod research in Berkeley. ie. reliable info.
http://www.ucmp.berkeley.edu/arthrop...ame=l_maculata
edit:
yes, to make a burrow, this species secretes mucus to get the sand to stick together and not collapse... basically they live in snot holes
edit 2: how do you know it's a girl? did you get a peek to see that it didn't have gonopods (male mantids have two penises)? the fact that you mention proportionally very large spearing arms relative to the body says male to me (at least in this species). plus the rarity of females.