Am i greek? dont understand you...
Sumps are a valuable addition to any marine tank, but, they are not neccesary. Yes, there is lots of valuable point to have one, but you dont NEED one...
You dont need to buy live sand, you can buy any sugar grain size aragonite sand and get a few cups of live sand from a fellow reef keeper...
An eheim 1250, if my knowledge is correct, is a pump rather than a powerhead..you may need to review that one...
Your Jewel 70 tank could turn into a lovely little marine system, no reason at all why not...
Anymore questions, please just ask...
Niko