I think you guys are not in much serious trouble in having the H. jayakari scorpions around. What you must be careful of is if you get any Arabian fat tailed scorpions in your house (a dark black species with enlarged tail segments). Just run a search on here for pics. Their scientific name literally translates to 'man killer' and are one of the most dangerous species in the world, apparently. I've seen many in the deserts. Sorry, don't mean to scare the creepers out of you but just a word of caution.
Your 'giant centipede' sounds like Scolopendrida mirabilis (or locally called the 44 legged lady as Ahmed educated me). Have a look at one of my pics on FB - https://www.facebook.com/#!/photo.ph...type=3&theater. Was it similar? There aren't too many of these in this area but this one is most common I think.