Build an Online Store

Hello, we are using cs cart multi-vendor 4.3.6 platform on Amzon ec 2 . As control panel we are using webmin + Virtualmin on this instance . No we need some fix on it here : 1) Please see snapshot name cs1 yo can see here in blue box there virtual memory is showing 0 so you need set correct it. 2) when we connect it thru FTP like Filezilla than we cant able to edit any file even a text file because after edit direct on FileZilla its can't uploaded & another problem is FileZilla work only in active mode not working in passive mode need to fix it. 3) we already installed php 7 on our instance but when we active it please see cs2 than website showing error please see cs3 4) We give 777 permission to image folder in our public_html patch but in our cs cart admin panel when try to upload a product image its not showing correct please see cs4 5) we are using php mail for all order related mail all working fine . But sometimes it take more time to deliver to inbox . Nee to fix this issue also . 6) We want to ask some thinks about webmin/virtualmin you need to explain only Thanks